Methods and systems for providing calibration point acceptance criteria for calibrating an analyte sensor

ABSTRACT

A method and transceiver for calibrating an analyte sensor using one or more reference measurements. In some embodiments, the method may include receiving a first reference analyte measurement (RM1) and determining whether the RM1 is unexpected. In some embodiments, the method may include, if the RM1 was determined to be unexpected, receiving a second reference analyte measurement (RM2). In some embodiments, the method may include determining whether one or more of the RM1 and the RM2 are acceptable as calibration points. In some embodiments, the method may include, if one or more of the RM1 and the RM2 are determined to be acceptable as calibration points, accepting one or more of the RM1 and the RM2 as calibration points. In some embodiments, the method may include calibrating the analyte sensor using at least one or more of the RM1 and the RM2 as calibration points.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims the benefit of priority to U.S.Provisional Application Ser. No. 62/520,852, filed on Jun. 16, 2017,which is incorporated herein by reference in its entirety.

BACKGROUND Field of Invention

The present invention relates to calibrating an analyte sensor in ananalyte monitoring system. More specifically, aspects of the presentinvention relate to determining whether a reference measurement isacceptable for calibrating the analyte sensor.

Discussion of the Background

Analyte monitoring systems may be used to measure analyte levels, suchas analyte concentrations. One type of analyte monitoring system is acontinuous glucose monitoring (CGM) system. A CGM system measuresglucose levels throughout the day and can be very useful in themanagement of diabetes. Analyte monitoring systems require calibration(and re-calibration) to maintain sensor accuracy and sensitivity. Thecalibration may be, for example and without limitation, performed dailyor twice-daily. The calibration may be performed using referencemeasurements. The reference measurements may be, for example and withoutlimitation, self-monitoring blood glucose (SMBG) measurements. Thereference measurements may be, for example and without limitation,obtained from finger-stick blood samples.

At least in the home environment, reference measurements are frequentlyerroneous. If an analyte monitoring system performs calibration using anerroneous analyte measurement as a calibration point, the analytemonitoring system may produce analyte measurements that are erroneousand inaccurate. Accordingly, systems and methods that prevent inaccuratereference measurements from negatively affecting calibration are needed.

One method for determining whether to accept or reject a referencemeasurement as a calibration point considers one or more of (i) whetherthe reference measurement is within the display range of the analytemonitoring system and (ii) whether the rate of change of the most recentanalyte measurement taken by the analyte monitoring system is slowenough for calibration. When the reference measurement is a glucosemeasurement, the display range of the analyte monitoring system may be,for example and without limitation, between 40 and 400 mg/dL. When thereference measurement is a glucose measurement, the rate of change rangeacceptable for calibration may be, for example and without limitation,between −2.5 mg/dL/min and 2.5 mg/dL/min. If one or more of thereference measurement and the rate of change criteria is not satisfied,then the analyte monitoring system may reject the reference measurement.This may eliminate the most inaccurate of the erroneous referencemeasurements from being used as calibration points. However, inaccuratereference measurements within the display range of the analytemonitoring system are not prevented from negatively affecting thecalibration process. Accordingly, improved methods and analytemonitoring systems are needed to improve calibration reliability and theaccuracy of analyte measurements.

SUMMARY

Aspects of the present invention relate to improving calibrationreliability and analyte measurement accuracy by identifying erroneousreference measurements and excluding them from use as calibrationpoints. Even a reference measurement within the display range of theanalyte monitoring system may have a large error. If calibration wereperformed using an inaccurate reference measurement, the error in thereference measurement would cause errors in the calculation ofsubsequent analyte measurements using sensor data received from ananalyte sensor. Aspects of the present invention may relate to acalibration point acceptance process that may prevent erroneousreference measurements from being used as calibration points and,thereby, improve accuracy of sensor measurements. The improvement insensor measurement accuracy may limit the number of false alerts relatedto high or low analyte levels, which may be especially helpful overnightwhen a user is trying to sleep.

One aspect of the invention may provide a method of calibrating ananalyte sensor using one or more reference measurements. The method mayinclude receiving a first reference analyte measurement (RM1). Themethod may include determining that the RM1 is unexpected. The methodmay include, after determining that the RM1 is unexpected, receiving asecond reference analyte measurement (RM2). The method may includedetermining that one or more of the RM1 and the RM2 are acceptable ascalibration points. The method may include accepting one or more of theRM1 and the RM2 as calibration points. The method may includecalibrating the analyte sensor using at least one or more of the RM1 andthe RM2 as calibration points.

In some embodiments, the RM1 may be a self-monitoring blood glucose(SMBG) measurement obtained from a finger-stick blood sample. In someembodiments, determining that the RM1 is unexpected may includedetermining that the RM1 is not within a threshold amount of a sensoranalyte measurement.

In some embodiments, the method may include one or more of receivingsensor data from the analyte sensor, using the sensor data to calculatea first sensor analyte measurement (SM1) without RM1 as a calibrationpoint, and using the sensor data to calculate a second sensor analytemeasurement (SM2) with the RM1 as a calibration point. In someembodiments, determining that one or more of the RM1 and the RM2 areacceptable as calibration points may include comparing the RM2 with oneor more of the SM1 and the SM2. In some embodiments, determining thatone or more of the RM1 and the RM2 are acceptable as calibration pointsmay include determining that the difference between the RM2 and the SM2is within a threshold amount, and determining that the RM2 is closer tothe SM2 than to the SM1. In some embodiments, accepting one or more ofthe RM1 and the RM2 as calibration points may include accepting both theRM1 and the RM2 as calibration points. In some embodiments, calibratingthe analyte sensor may use at least the RM1 and the RM2 as calibrationpoints.

In some embodiments, determining that one or more of the RM1 and the RM2are acceptable as calibration points may include one or more ofdetermining that the difference between the RM2 and the SM1 is withinthe threshold amount; and determining that the RM2 is closer to the SM1than to the SM2. In some embodiments, accepting one or more of the RM1and the RM2 as calibration points may include accepting the RM2 as acalibration point and not accepting the RM1 as a calibration point. Insome embodiments, calibrating the analyte sensor may use at least theRM2 as a calibration point and may not use the RM1 as a calibrationpoint.

In some embodiments, accepting one or more of the RM1 and the RM2 ascalibration points may include storing one or more of the RM1 and theRM2 in a calibration point memory. In some embodiments, calibrating theanalyte sensor may include calibrating a conversion function used toconvert sensor data received from the analyte sensor into a sensoranalyte measurement. In some embodiments, the method may include storingthe unexpected RM1 in a calibration point memory. In some embodiments,determining that one or more of the RM1 and the RM2 are acceptable ascalibration points may include determining that the RM2 is acceptableand that the RM1 is not acceptable. In some embodiments, the method mayinclude, in response to determining that RM1 is not acceptable, deletingthe RM1 from the calibration point memory.

Another aspect of the invention may provide a method of calibrating ananalyte sensor using one or more reference measurements. The method mayinclude receiving a first reference analyte measurement (RM1). Themethod may include determining that the RM1 is unexpected. The methodmay include, after determining that the RM1 is unexpected, receiving asecond reference analyte measurement (RM2). The method may includedetermining that the RM2 is unexpected. The method may include, afterdetermining that the RM2 is unexpected, receiving a third referenceanalyte measurement (RM3). The method may include accepting one or moreof the RM2 and the RM3 as calibration points. The method may includecalibrating the analyte sensor using at least one or more of the RM2 andthe RM3 as calibration points.

In some embodiments, the method may include, after determining that theRM2 is unexpected, accepting the RM1. In some other embodiments, themethod may include, after determining that the RM2 is unexpected,rejecting the RM1.

Yet another aspect of the invention may provide a transceiver includinga sensor interface device, a display interface device, and a processor.The sensor interface device may be configured to receive sensor dataconveyed by an analyte sensor. The display interface device may beconfigured to convey information to a display device and to receiveinformation from the display device. The processor may be configured toreceive a first reference analyte measurement (RM1) from the displaydevice via the display interface device. The processor may be configuredto determine that the RM1 is unexpected. The processor may be configuredto, after determining that the RM1 is unexpected, receive a secondreference analyte measurement (RM2) from the display device via thedisplay interface device. The processor may be configured to determinethat one or more of the RM1 and the RM2 are acceptable as calibrationpoints. The processor may be configured to accept one or more of the RM1and the RM2 as calibration points. The processor may be configured tocalibrate the analyte sensor using at least one or more of the RM1 andthe RM2 as calibration points.

Still another aspect of the invention may provide a transceiverincluding a sensor interface device, a display interface device, and aprocessor. The sensor interface device may be configured to receivesensor data conveyed by the analyte sensor. The display interface devicemay be configured to convey information to a display device and toreceive information from the display device. The processor may beconfigured to receive a first reference analyte measurement (RM1) fromthe display device via the display interface device. The processor maybe configured to determine that the RM1 is unexpected. The processor maybe configured to, after determining that the RM1 is unexpected, receivea second reference analyte measurement (RM2) from the display device viathe display interface device. The processor may be configured todetermine that the RM2 is unexpected. The processor may be configuredto, after determining that the RM2 is unexpected, receive a thirdreference analyte measurement (RM3) from the display device via thedisplay interface device. The processor may be configured to accept oneor more of the RM2 and the RM3 as calibration points. The processor maybe configured to calibrate the analyte sensor using at least one or moreof the RM2 and the RM3 as calibration points.

In some embodiments, the processor may be further configured to, afterdetermining that the RM2 is unexpected, accept the RM1. In otherembodiments, the processor may be further configured to, afterdetermining that the RM2 is unexpected, reject the RM1.

Another aspect of the invention may provide a method including receivingone or more reference analyte measurements at a first rate. The methodmay include determining that a first reference analyte measurement (RM1)of the one or more reference analyte measurements received at the firstrate is an expected reference analyte measurement. The method mayinclude, after determining that the RM1 is an expected reference analytemeasurement, receiving one or more reference analyte measurements at asecond rate, wherein second rate is lower than the first rate.

In some embodiments, the method may further include determining that asecond reference analyte measurement (RM2) of the one or more referenceanalyte measurements received at the second rate is not an expectedreference analyte measurement and, after determining that the RM2 is notan expected reference analyte measurement, receiving one or morereference analyte measurements at the first rate. In some embodiments,determining that the RM1 is an expected reference analyte measurementmay include determining that the RM1 is within a threshold amount of asensor analyte measurement.

In some embodiments, the method may further include, before determiningthat the RM1 is an expected reference analyte measurement, causing adisplay device to prompt a user for reference measurements at the firstrate. In some embodiments, the method may further include, afterdetermining that the RM1 is an expected reference analyte measurement,causing a display device to prompt a user for reference measurements atthe second rate. In some embodiments, the method may further includeperforming a calibration using the RM1 as a calibration point.

Still another aspect of the invention may provide a transceiverincluding a display interface device and a processor. The displayinterface device may be configured to convey information to a displaydevice and to receive information from the display device. The processormay be configured to receive one or more reference analyte measurementsfrom the display device via the display interface device at a firstrate. The processor may be configured to determine whether a firstreference analyte measurement (RM1) of the one or more reference analytemeasurements received at the first rate is an expected reference analytemeasurement. The processor may be configured to, after determining thatthe RM1 is an expected reference analyte measurement, receive one ormore reference analyte measurements from the display device via thedisplay interface device at a second rate, wherein second rate is lowerthan the first rate.

In some embodiments, the processor may be further configured todetermine that a second reference analyte measurement (RM2) of the oneor more reference analyte measurements received at the second rate isnot an expected reference analyte measurement and, after determiningthat the RM2 is not an expected reference analyte measurement, receiveone or more reference analyte measurements from the display device viathe display interface device at the first rate. In some embodiments, thetransceiver may further include a sensor interface device configured toreceive sensor data conveyed by an analyte sensor, and determining thatthe RM1 is an expected reference analyte measurement may includedetermining that the RM1 is within a threshold amount of a sensoranalyte measurement calculated using the sensor data received from theanalyte sensor via the sensor interface device.

In some embodiments, the processor may be further configured to, beforedetermining that the RM1 is an expected reference analyte measurement,cause a display device to prompt a user for reference measurements atthe first rate. In some embodiments, the processor may be furtherconfigured to, after determining that the RM1 is an expected referenceanalyte measurement, cause a display device to prompt a user forreference measurements at the second rate. In some embodiments, theprocessor may be further configured to perform a calibration using theRM1 as a calibration point.

Further variations encompassed within the systems and methods aredescribed in the detailed description of the invention below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate various, non-limiting embodiments ofthe present invention. In the drawings, like reference numbers indicateidentical or functionally similar elements.

FIG. 1 is a schematic view illustrating an analyte monitoring systemembodying aspects of the present invention.

FIG. 2 is a schematic view illustrating a sensor and transceiver of ananalyte monitoring system embodying aspects of the present invention.

FIG. 3 is cross-sectional, perspective view of a transceiver embodyingaspects of the invention.

FIG. 4 is an exploded, perspective view of a transceiver embodyingaspects of the invention.

FIG. 5 is a schematic view illustrating a transceiver embodying aspectsof the present invention.

FIG. 6 is a flow chart illustrating a process for controllinginitialization and calibration of an analyte monitoring system embodyingaspects of the present invention.

FIG. 7 is a flow chart illustrating a normal calibration processembodying aspects of the present invention.

FIG. 8 is a flow chart illustrating an unexpected calibration processembodying aspects of the present invention.

FIG. 9 is a flow chart illustrating an alternative unexpectedcalibration process embodying aspects of the present invention.

FIG. 10 is a flow chart illustrating another alternative unexpectedcalibration process embodying aspects of the present invention.

FIG. 11 is a flow chart illustrating an additional alternativeunexpected calibration process embodying aspects of the presentinvention.

FIG. 12 is a flow chart illustrating an alternative process forcontrolling initialization and calibration of an analyte monitoringsystem embodying aspects of the present invention.

FIG. 13 is a flow chart illustrating an alternative normal calibrationprocess embodying aspects of the present invention

FIG. 14 is a flow chart illustrating an expected calibration processembodying aspects of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a schematic view of an exemplary analyte monitoring system 50embodying aspects of the present invention. The analyte monitoringsystem 50 may be a continuous analyte monitoring system (e.g., acontinuous glucose monitoring system). In some embodiments, the analytemonitoring system 50 may include one or more of an analyte sensor 100, atransceiver 101, and a display device 105. In some embodiments, thesensor 100 may be small, fully subcutaneously implantable sensormeasures analyte (e.g., glucose) concentrations in a medium (e.g.,interstitial fluid) of a living animal (e.g., a living human). However,this is not required, and, in some alternative embodiments, the sensor100 may be a partially implantable (e.g., transcutaneous) sensor or afully external sensor. In some embodiments, the transceiver 101 may bean externally worn transceiver (e.g., attached via an armband,wristband, waistband, or adhesive patch). In some embodiments, thetransceiver 101 may remotely power and/or communicate with the sensor toinitiate and receive the measurements (e.g., via near fieldcommunication (NFC)). However, this is not required, and, in somealternative embodiments, the transceiver 101 may power and/orcommunicate with the sensor 100 via one or more wired connections. Insome non-limiting embodiments, the transceiver 101 may be a smartphone(e.g., an NFC-enabled smartphone). In some embodiments, the transceiver101 may communicate information (e.g., one or more analyteconcentrations) wirelessly (e.g., via a Bluetooth™ communicationstandard such as, for example and without limitation Bluetooth LowEnergy) to a hand held application running on a display device 105(e.g., smartphone). In some embodiments, the analyte monitoring system50 may include a web interface for plotting and sharing of uploadeddata.

In some embodiments, as illustrated in FIG. 2, the transceiver 101 mayinclude an inductive element 103, such as, for example, a coil. Thetransceiver 101 may generate an electromagnetic wave or electrodynamicfield (e.g., by using a coil) to induce a current in an inductiveelement 114 of the sensor 100, which powers the sensor 100. Thetransceiver 101 may also convey data (e.g., commands) to the sensor 100.For example, in a non-limiting embodiment, the transceiver 101 mayconvey data by modulating the electromagnetic wave used to power thesensor 100 (e.g., by modulating the current flowing through a coil 103of the transceiver 101). The modulation in the electromagnetic wavegenerated by the transceiver 101 may be detected/extracted by the sensor100. Moreover, the transceiver 101 may receive sensor data (e.g.,measurement information) from the sensor 100. For example, in anon-limiting embodiment, the transceiver 101 may receive sensor data bydetecting modulations in the electromagnetic wave generated by thesensor 100, e.g., by detecting modulations in the current flowingthrough the coil 103 of the transceiver 101.

The inductive element 103 of the transceiver 101 and the inductiveelement 114 of the sensor 100 may be in any configuration that permitsadequate field strength to be achieved when the two inductive elementsare brought within adequate physical proximity.

In some non-limiting embodiments, as illustrated in FIG. 2, the sensor100 may be encased in a sensor housing 102 (i.e., body, shell, capsule,or encasement), which may be rigid and biocompatible. The sensor 100 mayinclude an analyte indicator element 106, such as, for example, apolymer graft coated, diffused, adhered, or embedded on or in at least aportion of the exterior surface of the sensor housing 102. The analyteindicator element 106 (e.g., polymer graft) of the sensor 100 mayinclude indicator molecules 104 (e.g., fluorescent indicator molecules)exhibiting one or more detectable properties (e.g., optical properties)based on the amount or concentration of the analyte in proximity to theanalyte indicator element 106. In some embodiments, the sensor 100 mayinclude a light source 108 that emits excitation light 329 over a rangeof wavelengths that interact with the indicator molecules 104. Thesensor 100 may also include one or more photodetectors 224, 226 (e.g.,photodiodes, phototransistors, photoresistors, or other photosensitiveelements). The one or more photodetectors (e.g., photodetector 224) maybe sensitive to emission light 331 (e.g., fluorescent light) emitted bythe indicator molecules 104 such that a signal generated by aphotodetector (e.g., photodetector 224) in response thereto that isindicative of the level of emission light 331 of the indicator moleculesand, thus, the amount of analyte of interest (e.g., glucose). In somenon-limiting embodiments, one or more of the photodetectors (e.g.,photodetector 226) may be sensitive to excitation light 329 that isreflected from the analyte indicator element 106 as reflection light333. In some non-limiting embodiments, one or more of the photodetectorsmay be covered by one or more filters that allow only a certain subsetof wavelengths of light to pass through (e.g., a subset of wavelengthscorresponding to emission light 331 or a subset of wavelengthscorresponding to reflection light 333) and reflect the remainingwavelengths. In some non-limiting embodiments, the sensor 100 mayinclude a temperature transducer 670. In some non-limiting embodiments,the sensor 100 may include a drug-eluting polymer matrix that dispersesone or more therapeutic agents (e.g., an anti-inflammatory drug).

In some embodiments, as illustrated in FIG. 2, the sensor 100 mayinclude a substrate 116. In some embodiments, the substrate 116 may be acircuit board (e.g., a printed circuit board (PCB) or flexible PCB) onwhich circuit components (e.g., analog and/or digital circuitcomponents) may be mounted or otherwise attached. However, in somealternative embodiments, the substrate 116 may be a semiconductorsubstrate having circuitry fabricated therein. The circuitry may includeanalog and/or digital circuitry. Also, in some semiconductor substrateembodiments, in addition to the circuitry fabricated in thesemiconductor substrate, circuitry may be mounted or otherwise attachedto the semiconductor substrate 116. In other words, in somesemiconductor substrate embodiments, a portion or all of the circuitry,which may include discrete circuit elements, an integrated circuit(e.g., an application specific integrated circuit (ASIC)) and/or otherelectronic components (e.g., a non-volatile memory), may be fabricatedin the semiconductor substrate 116 with the remainder of the circuitryis secured to the semiconductor substrate 116 and/or a core (e.g.,ferrite core) for the inductive element 114. In some embodiments, thesemiconductor substrate 116 and/or a core may provide communicationpaths between the various secured components.

In some embodiments, the one or more of the sensor housing 102, analyteindicator element 106, indicator molecules 104, light source 108,photodetectors 224, 226, temperature transducer 670, substrate 116, andinductive element 114 of sensor 100 may include some or all of thefeatures described in one or more of U.S. application Ser. No.13/761,839, filed on Feb. 7, 2013, U.S. application Ser. No. 13/937,871,filed on Jul. 9, 2013, and U.S. application Ser. No. 13/650,016, filedon Oct. 11, 2012, all of which are incorporated by reference in theirentireties. Similarly, the structure and/or function of the sensor 100and/or transceiver 101 may be as described in one or more of U.S.application Ser. Nos. 13/761,839, 13/937,871, and 13/650,016.

Although in some embodiments, as illustrated in FIG. 2, the sensor 100may be an optical sensor, this is not required, and, in one or morealternative embodiments, sensor 100 may be a different type of analytesensor, such as, for example, an electrochemical sensor, a diffusionsensor, or a pressure sensor. Also, although in some embodiments, asillustrated in FIGS. 1 and 2, the analyte sensor 100 may be a fullyimplantable sensor, this is not required, and, in some alternativeembodiments, the sensor 100 may be a transcutaneous sensor having awired connection to the transceiver 101. For example, in somealternative embodiments, the sensor 100 may be located in or on atranscutaneous needle (e.g., at the tip thereof). In these embodiments,instead of wirelessly communicating using inductive elements 103 and114, the sensor 100 and transceiver 101 may communicate using one ormore wires connected between the transceiver 101 and the transceivertranscutaneous needle that includes the sensor 100. For another example,in some alternative embodiments, the sensor 100 may be located in acatheter (e.g., for intravenous blood glucose monitoring) and maycommunicate (wirelessly or using wires) with the transceiver 101.

In some embodiments, the sensor 100 may include a transceiver interfacedevice. In some embodiments where the sensor 100 includes an antenna(e.g., inductive element 114), the transceiver interface device mayinclude the antenna (e.g., inductive element 114) of sensor 100. In someof the transcutaneous embodiments where there exists a wired connectionbetween the sensor 100 and the transceiver 101, the transceiverinterface device may include the wired connection.

FIGS. 3 and 4 are cross-sectional and exploded views, respectively, of anon-limiting embodiment of the transceiver 101, which may be included inthe analyte monitoring system illustrated in FIG. 1. As illustrated inFIG. 4, in some non-limiting embodiments, the transceiver 101 mayinclude a graphic overlay 204, front housing 206, button 208, printedcircuit board (PCB) assembly 210, battery 212, gaskets 214, antenna 103,frame 218, reflection plate 216, back housing 220, ID label 222, and/orvibration motor 928. In some non-limiting embodiments, the vibrationmotor 928 may be attached to the front housing 206 or back housing 220such that the battery 212 does not dampen the vibration of vibrationmotor 928. In a non-limiting embodiment, the transceiver electronics maybe assembled using standard surface mount device (SMD) reflow and soldertechniques. In one embodiment, the electronics and peripherals may beput into a snap together housing design in which the front housing 206and back housing 220 may be snapped together. In some embodiments, thefull assembly process may be performed at a single external electronicshouse. However, this is not required, and, in alternative embodiments,the transceiver assembly process may be performed at one or moreelectronics houses, which may be internal, external, or a combinationthereof. In some embodiments, the assembled transceiver 101 may beprogrammed and functionally tested. In some embodiments, assembledtransceivers 101 may be packaged into their final shipping containersand be ready for sale.

In some embodiments, as illustrated in FIGS. 3 and 4, the antenna 103may be contained within the housing 206 and 220 of the transceiver 101.In some embodiments, the antenna 103 in the transceiver 101 may be smalland/or flat so that the antenna 103 fits within the housing 206 and 220of a small, lightweight transceiver 101. In some embodiments, theantenna 103 may be robust and capable of resisting various impacts. Insome embodiments, the transceiver 101 may be suitable for placement, forexample, on an abdomen area, upper-arm, wrist, or thigh of a patientbody. In some non-limiting embodiments, the transceiver 101 may besuitable for attachment to a patient body by means of a biocompatiblepatch. Although, in some embodiments, the antenna 103 may be containedwithin the housing 206 and 220 of the transceiver 101, this is notrequired, and, in some alternative embodiments, a portion or all of theantenna 103 may be located external to the transceiver housing. Forexample, in some alternative embodiments, antenna 103 may wrap around auser's wrist, arm, leg, or waist such as, for example, the antennadescribed in U.S. Pat. No. 8,073,548, which is incorporated herein byreference in its entirety.

FIG. 5 is a schematic view of an external transceiver 101 according to anon-limiting embodiment. In some embodiments, the transceiver 101 mayhave a connector 902, such as, for example, a Micro-Universal Serial Bus(USB) connector. The connector 902 may enable a wired connection to anexternal device, such as a personal computer (e.g., personal computer109) or a display device 105 (e.g., a smartphone).

The transceiver 101 may exchange data to and from the external devicethrough the connector 902 and/or may receive power through the connector902. The transceiver 101 may include a connector integrated circuit (IC)904, such as, for example, a USB-IC, which may control transmission andreceipt of data through the connector 902. The transceiver 101 may alsoinclude a charger IC 906, which may receive power via the connector 902and charge a battery 908 (e.g., lithium-polymer battery). In someembodiments, the battery 908 may be rechargeable, may have a shortrecharge duration, and/or may have a small size.

In some embodiments, the transceiver 101 may include one or moreconnectors in addition to (or as an alternative to) Micro-USB connector904. For example, in one alternative embodiment, the transceiver 101 mayinclude a spring-based connector (e.g., Pogo pin connector) in additionto (or as an alternative to) Micro-USB connector 904, and thetransceiver 101 may use a connection established via the spring-basedconnector for wired communication to a personal computer (e.g., personalcomputer 109) or a display device 105 (e.g., a smartphone) and/or toreceive power, which may be used, for example, to charge the battery908.

In some embodiments, the transceiver 101 may have a wirelesscommunication IC 910, which enables wireless communication with anexternal device, such as, for example, one or more personal computers(e.g., personal computer 109) or one or more display devices 105 (e.g.,a smartphone). In one non-limiting embodiment, the wirelesscommunication IC 910 may employ one or more wireless communicationstandards to wirelessly transmit data. The wireless communicationstandard employed may be any suitable wireless communication standard,such as an ANT standard, a Bluetooth standard, or a Bluetooth Low Energy(BLE) standard (e.g., BLE 4.0). In some non-limiting embodiments, thewireless communication IC 910 may be configured to wirelessly transmitdata at a frequency greater than 1 gigahertz (e.g., 2.4 or 5 GHz). Insome embodiments, the wireless communication IC 910 may include anantenna (e.g., a Bluetooth antenna). In some non-limiting embodiments,the antenna of the wireless communication IC 910 may be entirelycontained within the housing (e.g., housing 206 and 220) of thetransceiver 101. However, this is not required, and, in alternativeembodiments, all or a portion of the antenna of the wirelesscommunication IC 910 may be external to the transceiver housing.

In some embodiments, the transceiver 101 may include a display interfacedevice, which may enable communication by the transceiver 101 with oneor more display devices 105. In some embodiments, the display interfacedevice may include the antenna of the wireless communication IC 910and/or the connector 902. In some non-limiting embodiments, the displayinterface device may additionally include the wireless communication IC910 and/or the connector IC 904.

In some embodiments, the transceiver 101 may include voltage regulators912 and/or a voltage booster 914. The battery 908 may supply power (viavoltage booster 914) to radio-frequency identification (RFID) reader IC916, which uses the inductive element 103 to convey information (e.g.,commands) to the sensor 101 and receive information (e.g., measurementinformation) from the sensor 100. In some non-limiting embodiments, thesensor 100 and transceiver 101 may communicate using near fieldcommunication (NFC) (e.g., at a frequency of 13.56 MHz). In theillustrated embodiment, the inductive element 103 is a flat antenna. Insome non-limiting embodiments, the antenna may be flexible. However, asnoted above, the inductive element 103 of the transceiver 101 may be inany configuration that permits adequate field strength to be achievedwhen brought within adequate physical proximity to the inductive element114 of the sensor 100. In some embodiments, the transceiver 101 mayinclude a power amplifier 918 to amplify the signal to be conveyed bythe inductive element 103 to the sensor 100.

The transceiver 101 may include a peripheral interface controller (PIC)microcontroller 920 and memory 922 (e.g., Flash memory), which may benon-volatile and/or capable of being electronically erased and/orrewritten. The PIC microcontroller 920 may control the overall operationof the transceiver 101. For example, the PIC microcontroller 920 maycontrol the connector IC 904 or wireless communication IC 910 totransmit data via wired or wireless communication and/or control theRFID reader IC 916 to convey data via the inductive element 103. The PICmicrocontroller 920 may also control processing of data received via theinductive element 103, connector 902, or wireless communication IC 910.

In some embodiments, the transceiver 101 may include a sensor interfacedevice, which may enable communication by the transceiver 101 with asensor 100. In some embodiments, the sensor interface device may includethe inductive element 103. In some non-limiting embodiments, the sensorinterface device may additionally include the RFID reader IC 916 and/orthe power amplifier 918. However, in some alternative embodiments wherethere exists a wired connection between the sensor 100 and thetransceiver 101 (e.g., transcutaneous embodiments), the sensor interfacedevice may include the wired connection.

In some embodiments, the transceiver 101 may include a display 924(e.g., liquid crystal display and/or one or more light emitting diodes),which PIC microcontroller 920 may control to display data (e.g., analyteconcentration values). In some embodiments, the transceiver 101 mayinclude a speaker 926 (e.g., a beeper) and/or vibration motor 928, whichmay be activated, for example, in the event that an alarm condition(e.g., detection of a hypoglycemic or hyperglycemic condition) is met.The transceiver 101 may also include one or more additional sensors 930,which may include an accelerometer and/or temperature sensor, that maybe used in the processing performed by the PIC microcontroller 920.

In some embodiments, the transceiver 101 may be a body-worn transceiverthat is a rechargeable, external device worn over the sensorimplantation or insertion site. The transceiver 101 may supply power tothe proximate sensor 100, calculate analyte concentrations from datareceived from the sensor 100, and/or transmit the calculated analyteconcentrations to a display device 105 (see FIG. 1). Power may besupplied to the sensor 100 through an inductive link (e.g., an inductivelink of 13.56 MHz). In some embodiments, the transceiver 101 may beplaced using an adhesive patch or a specially designed strap or belt.The external transceiver 101 may read measured analyte data from asubcutaneous sensor 100 (e.g., up to a depth of 2 cm or more). Thetransceiver 101 may periodically (e.g., every 2, 5, or 10 minutes) readsensor data and calculate an analyte concentration and an analyteconcentration trend. From this information, the transceiver 101 may alsodetermine if an alert and/or alarm condition exists, which may besignaled to the user (e.g., through vibration by vibration motor 928and/or an LED of the transceiver's display 924 and/or a display of adisplay device 105). The information from the transceiver 101 (e.g.,calculated analyte concentrations, calculated analyte concentrationtrends, alerts, alarms, and/or notifications) may be transmitted to adisplay device 105 (e.g., via Bluetooth Low Energy with AdvancedEncryption Standard (AES)-Counter CBC-MAC (CCM) encryption) for displayby a mobile medical application (MMA) being executed by the displaydevice 105. In some non-limiting embodiments, the MMA may providealarms, alerts, and/or notifications in addition to any alerts, alarms,and/or notifications received from the transceiver 101. In oneembodiment, the MMA may be configured to provide push notifications. Insome embodiments, the transceiver 101 may have a power button (e.g.,button 208) to allow the user to turn the device on or off, reset thedevice, or check the remaining battery life. In some embodiments, thetransceiver 101 may have a button, which may be the same button as apower button or an additional button, to suppress one or more usernotification signals (e.g., vibration, visual, and/or audible) of thetransceiver 101 generated by the transceiver 101 in response todetection of an alert or alarm condition.

In some embodiments, the transceiver 101 of the analyte monitoringsystem 50 may receive raw signals indicative of an amount orconcentration of an analyte in proximity to the analyte indicatorelement 106 of the analyte sensor 100. In some embodiments, thetransceiver 101 may receive the raw signals from the sensor 100periodically (e.g., every 5, 10, or 20 minutes). In some embodiments,the raw signals may include one or more measurements (e.g., one or moremeasurements indicative of the level of emission light 331 from theindicator molecules 104 as measured by the photodetector 224, one ormore measurements indicative of the level of reference light 333 asmeasured by photodetector 226, and/or one or more temperaturemeasurements as measured by the temperature transducer 670). In someembodiments, the transceiver 101 may use the received raw signals tocalculate analyte concentration. In some embodiments, the transceiver100 may store one or more calculated analyte concentrations (e.g., inmemory 922). In some embodiments, the transceiver 100 may convey one ormore calculated analyte concentrations to the display device 105, andthe display device 105 may display the one or more calculated analyteconcentrations.

In some embodiments, the analyte monitoring system 50 may calibrate theconversion of raw signals to analyte concentration. In some embodiments,the calibration may be performed approximately periodically (e.g.,approximately every 12 or 24 hours). In some embodiments, thecalibration may be performed using one or more reference measurements(e.g., one or more self-monitoring blood glucose (SMBG) measurements),which may be entered into the analyte monitoring system 50 using theuser interface of the display device 105. In some embodiments, thetransceiver 101 may receive the one or more reference measurements fromthe display device 105 and perform the calibration. One or more of thereference measurements may be erroneous and may lead to erroneousanalyte measurement calculation if used as a calibration point for thecalibrating of the conversion of raw sensor data to analytemeasurements. Accordingly, the analyte monitoring system 5 (e.g., thetransceiver 101) may determine whether to accept (or reject) referencemeasurements as calibration points in the calibration process. Thiscalibration point acceptance process may be used to prevent erroneousreference measurements from being used as calibration points whencalibrating the function used to convert raw sensor data (e.g., lightand/or temperature measurements) into analyte measurements (e.g.,analyte concentrations). In this way, the calibration point acceptanceprocess may increase the accuracy and/or precision of the analytemeasurements.

FIG. 6 is a flow chart illustrating a process 600 for controllinginitialization and calibration of an analyte monitoring system 50. Insome embodiments, the transceiver 101 may perform one or more steps ofthe control process 600. In some non-limiting embodiments, the PICmicrocontroller 920 of the transceiver 101 may perform one or more stepsof the control process 600. In some embodiments, the process 600 maybegin after insertion or implantation of the analyte sensor 100.

In some embodiments, the process 600 may begin with a warm up phase 602in which the transceiver 101 allows the sensor 100 to adjust to beingfully or partially in the body. In some non-limiting embodiments, thewarm up phase 602 may give the analyte indicator element 106 time tohydrate. In some non-limiting embodiments, the transceiver 101 stays inthe warm up phase 602 for a predetermined period of time such as, forexample and without limitation, 12 or 24 hours. However, this is notrequired, and, in some alternative embodiments, the transceiver 101 maymonitor sensor conditions during the warm up phase 602 and exit the warmup phase 602 after the sensor conditions have stabilized. In someembodiments, after completion of the warm up phase 602, the process 600may proceed to an initialization phase 604. In some alternativeembodiments, the warm up phase 602 may not be necessary (e.g., when theanalyte sensor 100 is an external sensor or does not need time toacclimate to being inside the body). In these alternative embodiments,the process 600 may begin in an initialization step 604.

In some embodiments, in the initialization phase 604, the transceiver101 may receive sensor data. In some non-limiting embodiments, thetransceiver 101 may receive the sensor data periodically (e.g., every 2,5, or 10 minutes). In some embodiments, in the initialization phase 604,the transceiver 101 may receive one or more reference measurements. Insome non-limiting embodiments, the transceiver 101 may receive three ormore reference measurements in the initialization phase 604. In somenon-limiting embodiments, the transceiver 101 may receive the referencemeasurements periodically (e.g., approximately every 6 hours). In someembodiments, the transceiver 101 may store the reference measurements ina calibration point memory, which may be, for example and withoutlimitation, a circular buffer. In some embodiments, the transceiver 101may use the one or more reference measurements as calibration points toperform an initial calibration of the conversion function used tocalculate analyte measurements from the sensor data. In someembodiments, the transceiver 101 may receive the one or more referencemeasurements from the display device 105. In some non-limitingembodiments, the transceiver 101 may cause the display device 105 toprompt a user for the one or more reference measurements, and, inresponse, the user may enter the one or more reference measurements intothe display device 105.

In some non-limiting embodiments, during the initialization phase 604,no analyte measurements are displayed to the user. In some embodiments,after the completion of the initialization phase 604, the process 600may proceed to a normal calibration phase 606. In some embodiments, thenormal calibration phase 606 may be a steady state phase. In somenon-limiting embodiments, although not shown in FIG. 6, if thetransceiver 101 determines that one or more references measurementsreceived during the initialization phase 604 are unexpected, the process600 may proceed from the initialization phase 604 to an unexpectedcalibration phase 608 (instead of proceeding to the normal calibrationphase 606).

In some embodiments, in the normal calibration phase 606, thetransceiver 101 may receive sensor data and calculate analytemeasurements using the conversion function and the received sensor data.In some non-limiting embodiments, the transceiver 101 may receive thesensor data periodically (e.g., every 2, 5, or 10 minutes). In someembodiments, the transceiver 101 may display one or more analytemeasurements. In some non-limiting embodiments, in the normalcalibration phase 606, the transceiver 101 may display the one or moreanalyte measurements by transmitting them to the display device 105 fordisplay.

In some embodiments, in the normal calibration phase 606, thetransceiver 101 may receive one or more reference measurements. In somenon-limiting embodiments, the transceiver 101 may receive the referencemeasurements periodically (e.g., approximately every 12 hours). In somenon-limiting embodiments, the transceiver 101 may receive the referencemeasurements less frequently than in the initialization phase 604.However, this is not required. It is also not required that thetransceiver 101 receive reference measurements periodically, and, insome alternative embodiments, the transceiver 101 may receive referencemeasurements on an as-needed basis (e.g., as determined by thetransceiver 101 by analyzing the sensor data). In some embodiments, thetransceiver 101 may receive the reference measurements from the displaydevice 105. In some non-limiting embodiments, in the normal calibrationphase 606, the transceiver 101 may cause the display device 105 toprompt a user for the one or more reference measurements, and, inresponse, the user may enter the one or more reference measurements intothe display device 105.

In some embodiments, in the normal calibration phase 606, thetransceiver 101 may determine whether to accept the referencemeasurement or to treat the reference measurement as unexpected. In somenon-limiting embodiments, the transceiver 101 may determine whether toaccept a received reference measurement by comparing the referencemeasurement to the most-recent sensor measurement (i.e., the most-recentanalyte measurement calculated by the conversion function using receivedsensor data). In some embodiments, if the transceiver 101 determinesthat the reference measurement is acceptable, the transceiver 101 maycalibrate (or re-calibrate or update) the conversion function using thereference point as a calibration point. In some embodiments, if thetransceiver 101 determines that a reference measurement is unexpected,the process 600 may proceed to an unexpected calibration phase 608.

In some embodiments, during the unexpected calibration phase 608, thetransceiver 101 may receive a new reference measurement. In someembodiments, the transceiver 101 may use the new reference measurementto determine whether one or both of the unexpected reference measurementand the conversion function, which was used to calculate the sensormeasurement to which the unexpected reference measurement was compared,were erroneous. If the transceiver 101 determines that only theunexpected measurement was erroneous, the transceiver 101 may reject theunexpected measurement, accept the new reference measurement as acalibration point, and perform a calibration of the conversion function.If the transceiver 101 determines that only the conversion function waserroneous, the transceiver 101 may accept both the unexpected and newreference measurements as calibration points and perform a calibrationof the calibration function. If the transceiver 101 accepts one or moreof the reference measurements, the process 600 may proceed back to thenormal calibration phase 606. Otherwise, the transceiver 101 may tryagain with another new reference measurement, or the process 600 mayproceed to a sensor dropout phase 610.

In some embodiments, in the sensor dropout phase 610, the transceiver101 may receive sensor data from the sensor 100, but no analytemeasurements are displayed to the user. In some embodiments, the process600 may remain in the dropout phase 610 for a period of time (e.g., atleast six hours) before proceeding back to the initialization phase 604.However, the sensor dropout phase 610 is not necessary, and, in somealternative embodiments, the process 600 may proceed directly to theinitialization phase 604 from the unexpected calibration phase 608.

FIG. 7 is a flow chart illustrating a normal calibration process 700,which may be performed during the normal calibration phase 606 of thecontrol process 600 illustrated in FIG. 6. In some embodiments, thetransceiver 101 may perform one or more steps of the normal calibrationprocess 700. In some non-limiting embodiments, the PIC microcontroller920 of the transceiver 101 may perform one or more steps of the normalcalibration process 700.

In some embodiments, the normal calibration process 700 may include astep 702 in which the transceiver 101 determines whether the transceiver101 has received sensor data (e.g., light and/or temperaturemeasurements) from the sensor 100. In some embodiments, the sensor datamay be received following a command (e.g., a measurement command or aread sensor data command) conveyed from the transceiver 101 to thesensor 100. However, this is not required, and, in some alternativeembodiments, the sensor 100 may control when sensor data is conveyed tothe transceiver 101, or the sensor 100 may continuously convey sensordata to the transceiver 101. In some non-limiting embodiments, thetransceiver 101 may receive the sensor data periodically (e.g., every 2,5, or 10 minutes). In some embodiments, the transceiver 101 may receivethe sensor data wirelessly. For example and without limitation, in somenon-limiting embodiments, the transceiver 101 may receive the sensordata by detecting modulations in an electromagnetic wave generated bythe sensor 100, e.g., by detecting modulations in the current flowingthrough the coil 103 of the transceiver 101. However, this is notrequired, and, in some alternative embodiments, the transceiver 101 mayreceive the sensor data via a wired connection to the sensor 100. Insome non-limiting embodiments, if the sensor has received sensor data,the normal calibration process 700 may proceed from step 702 to ameasurement calculation step 704. In some non-limiting embodiments, ifthe transceiver 101 has not received sensor data, the normal calibrationprocess 700 may proceed from step 702 to a step 706.

In some non-limiting embodiments, the normal calibration process 700 mayinclude the measurement calculation step 704. In some embodiments, thestep 704 may include calculating a sensor measurement SM1 using thecurrent calibration function and the received sensor data. In someembodiments, the sensor measurement SM1 may be a measurement of theamount or concentration of the analyte in proximity to the analyteindicator element 106. In some embodiments, in step 704, the transceiver101 may display the calculated sensor measurement SM1. In somenon-limiting embodiments, the transceiver 101 may display the sensormeasurement SM1 by transmitting it to the display device 105 fordisplay.

In some non-limiting embodiments, the normal calibration process 700 mayinclude the step 706 in which the transceiver 101 determines whether thetransceiver 101 has received a reference measurement RM1. The referencemeasurement RM1 may be, for example and without limitation, an SMBGmeasurement obtained from, for example and without limitation, afinger-stick blood sample. In some embodiments, the transceiver 101 mayreceive reference measurements periodically or on an as-needed basis. Insome embodiments, the transceiver 101 may receive the referencemeasurement RM1 from the display device 105. In some non-limitingembodiments, the transceiver 101 may cause the display device 105 toprompt a user for the reference measurement RM1, and, in response, theuser may enter the reference measurement RM1 into the display device105. If the transceiver 101 has not received a reference measurementRM1, the normal calibration process 700 may proceed back to step 702 andcontinue using the current calibration function to calculate sensormeasurements when sensor data is received until a reference measurementRM1 is received. If the transceiver 101 has received a referencemeasurement RM1, the normal calibration process 700 may proceed to astep 708.

In some non-limiting embodiments, the normal calibration process 700 mayinclude the step 708 in which the transceiver 101 determines whether toaccept the reference measurement RM1 or to treat the referencemeasurement RM1 as unexpected. In some non-limiting embodiments, thestep 708 may include comparing the reference measurement RM1 and themost-recent sensor measurement SM1 (i.e., the most-recent analytemeasurement calculated by the conversion function using received sensordata). In some embodiments, the most-recent sensor measurement SM1 mayhave been calculated within a certain amount of time, such as, forexample and without limitation, 5, 10, or 20 minutes. In somenon-limiting embodiments, the step 708 may include determining whetherthere is a large discrepancy between the reference measurement RM1 andthe most-recent sensor measurement SM1. In some non-limitingembodiments, the transceiver 101 may determine that a referencemeasurement RM1 is unexpected if there is a large discrepancy betweenthe reference measurement RM1 and the most-recent sensor measurementSM1. In non-limiting some embodiments, the transceiver 101 may determinethat the reference measurement is acceptable if the difference betweenthe reference measurement RM1 and the sensor measurement SM1 is within athreshold amount. In some non-limiting embodiments, the threshold amountmay be a percentage of the sensor measurement SM1 (e.g., ±30% of SM1) ora deviation of the sensor measurement SM1 (e.g., ±10 mg/dL of SM1).

In some non-limiting embodiments, the threshold amount may be a fixedthreshold. However, this is not required, and, in some alternativeembodiments, the threshold amount may vary. In some non-limitingalternative embodiments, the threshold amount may vary based on one ormore of the sensor measurement SM1 and the reference measurement RM1. Insome non-limiting embodiments where the threshold amount varies based onreference amount RM1, the reference measurement range may be dividedinto two or more sub-ranges, and the transceiver 101 may use a differentthreshold for each of the sub-ranges. That is, in some non-limitingembodiments, if the reference measurement RM1 falls into a secondreference measurement sub-range, the transceiver 101 may use a secondthreshold when determining whether the reference measurement RM1 isacceptable. For example and without limitation, in one non-limitingalternative embodiment where the threshold amount varies based onreference measurement sub-ranges, the reference measurement range may bedivided into the following five sub-ranges: (i) less than 70 mg/dL, (ii)greater than or equal to 70 mg/dL and less than 140 mg/dL, (iii) greaterthan or equal to 140 mg/dL and less than 180 mg/dL, (iv) greater than orequal to 180 mg/dL and less than 240 mg/dL, and (v) greater than orequal to 240 mg/dL, and the transceiver 101 may use a differentthreshold amount for each of the five sub-ranges. However, this is notrequired, and some alternative embodiments may use different sub-rangesand/or a different number of sub-ranges. In some other alternativeembodiments having a varying threshold amount, the transceiver 101 mayuse a linear or non-linear formula to calculate the threshold amountthat should be used for a particular reference measurement RM1 or sensormeasurement SM1.

In some embodiments, if the transceiver 101 determines that thereference measurement RM1 is unexpected, the normal calibration process700 may proceed from step 708 to a step 710 in which the transceiver 101leaves the normal calibration phase and enters an unexpected calibrationphase (e.g., the unexpected calibration phase 608 of FIG. 6). In someembodiments, if the transceiver 101 determines that the referencemeasurement RM1 is acceptable, the normal calibration process 700 mayproceed from step 708 to a step 712.

In some embodiments, in step 712, the transceiver 101 may accept thereference measurement RM1 as a calibration point. In some non-limitingembodiments, accepting the reference measurement RM1 as a calibrationpoint may include storing the reference measurement RM1 in a calibrationpoint memory (e.g., a circular buffer). In some embodiments, in step712, the transceiver 101 may calibrate the conversion function used tocalculate analyte measurements from sensor data. In some non-limitingembodiments, the transceiver 101 may calibrate the conversion functionusing one or more of the calibration points stored in the calibrationpoint memory. In some embodiments, the one or more calibration pointsused to calibrate the conversion function may include the referencemeasurement RM1. In some non-limiting embodiments, the transceiver 101may assign weights to the one or more calibration points. In somenon-limiting embodiments, the transceiver 101 may assign weights basedon the age of the calibration points with less weight being given toolder calibration points. In some embodiments, the normal calibrationprocess 700 may proceed from step 712 to step 702, and the transceiver101 may use the updated conversion function to calculate sensormeasurements from subsequent sensor data.

FIG. 8 is a flow chart illustrating an unexpected calibration process800, which may be performed during the unexpected calibration phase 608of the control process 600 illustrated in FIG. 6. In some embodiments,the transceiver 101 may perform one or more steps of the unexpectedcalibration process 800. In some non-limiting embodiments, the PICmicrocontroller 920 of the transceiver 101 may perform one or more stepsof the unexpected calibration process 800.

In some embodiments, the unexpected calibration process 800 may includea step 802 in which the transceiver 101 determines whether thetransceiver 101 has received sensor data (e.g., light and/or temperaturemeasurements) from the sensor 100. In some non-limiting embodiments, ifthe sensor has received sensor data, the unexpected calibration process800 may proceed from step 802 to a measurement calculation step 804. Insome non-limiting embodiments, if the transceiver 101 has not receivedsensor data, the unexpected calibration process 800 may proceed fromstep 802 to a step 806.

In some non-limiting embodiments, the unexpected calibration process 800may include the measurement calculation step 804. In some embodiments,the step 804 may include calculating a sensor measurement SM1 using thecurrent calibration function, which does not take the referencemeasurement RM1 into account, and the received sensor data. In someembodiments, in step 804, the transceiver 101 may display the calculatedsensor measurement SM1. In some non-limiting embodiments, thetransceiver 101 may display the sensor measurement SM1 by transmittingit to the display device 105 for display.

In some embodiments, the unexpected calibration process 800 may includea step 806 in which the transceiver 101 determines whether thetransceiver 101 has received a reference measurement RM2. The referencemeasurement RM2 may be, for example and without limitation, an SMBGmeasurement obtained from, for example and without limitation, afinger-stick blood sample. In some non-limiting embodiments, thetransceiver 101 may receive the reference measurement RM2 at least aperiod of time (e.g., 1 minute, 5 minutes, 10 minutes, 15 minutes, 30minutes, 1 hour, etc.) after receiving the unexpected referencemeasurement RM1. In some embodiments, the transceiver 101 may receivethe reference measurement RM2 from the display device 105. In somenon-limiting embodiments, after the period of time has passed since theunexpected reference measurement RM1 was received, the transceiver 101may cause the display device 105 to prompt a user for the referencemeasurement RM2, and, in response, the user may enter the referencemeasurement RM2 into the display device 105. If the transceiver 101 hasnot received a reference measurement RM2, the unexpected calibrationprocess 800 may proceed back to step 802 and continue using the currentcalibration function, which does not take the reference measurement RM1into account, to calculate sensor measurements from sensor data until areference measurement RM2 is received. If the transceiver 101 hasreceived a reference measurement RM2, the unexpected calibration process800 may proceed to a step 808.

In some embodiments, the unexpected calibration process 800 may includea step 808 in which the transceiver 101 calculates a sensor measurementSM2 using a conversion function that takes the unexpected referencemeasurement RM1 into account as a calibration point. In somenon-limiting embodiments, in step 808, the transceiver 101 mayadditionally calculate a sensor measurement SM1 using a conversionfunction that does not take the unexpected reference measurement RM1into account as a calibration point.

In some embodiments, the unexpected calibration process 800 may includea step 810 in which the transceiver 101 determines whether one or moreof the reference measurements RM1 and RM2 are acceptable. In somenon-limiting embodiments, the step 810 may include comparing thereference measurement RM2 with the most-recent sensor measurement SM1,which was calculated by a conversion function that did not take theunexpected reference measurement RM1 into account, and with the sensormeasurement SM2, which was calculated by a conversion function that didtake the unexpected reference measurement RM1 into account.

In some non-limiting embodiments, the step 810 may include determiningwhether there is a large discrepancy between the reference measurementRM2 and one or more of the sensor measurements SM1 and SM2. Innon-limiting some embodiments, the transceiver 101 may determine whetherthe difference between the reference measurement RM2 and the sensormeasurement SM1 is within a threshold amount and whether the differencebetween the reference measurement RM2 and the sensor measurement SM2 iswithin the threshold amount. In some non-limiting embodiments, thethreshold amount may be a percentage of or deviation from sensormeasurement SM1. In some non-limiting embodiments, the threshold amountmay be a fixed, or the threshold amount may vary (e.g., based on thereference measurement RM2, sensor measurement SM1, or sensor measurementSM2). In some non-limiting embodiments, the step 810 may includedetermining whether the reference measurement RM2 is closer to thesensor measurement SM1 or sensor measurement SM2.

In some embodiments, in step 810, the transceiver 101 may determine thatreference measurement RM2 is acceptable if the transceiver 101determines both that (i) the difference between the referencemeasurement RM2 and the sensor measurement SM1, which was calculatedwithout taking the unexpected reference measurement RM1 into account, iswithin the threshold amount and (ii) the reference measurement RM2 iscloser to the sensor measurement SM1 than the sensor measurement SM2,which was calculated taking the unexpected reference measurement RM1into account. However, this is not required, and, in some alternativeembodiments, the transceiver 101 may determine that the referencemeasurement RM2 is acceptable in a different way. For example andwithout limitation, in one alternative embodiment, the transceiver 101may determine that the reference measurement RM2 is acceptable if onlyone of conditions (i) and (ii) is met.

In some embodiments, in step 810, the transceiver 101 may determine thatboth reference measurements RM1 and RM2 are acceptable if thetransceiver 101 determines both that (i) the difference between thereference measurement RM2 and the sensor measurement SM2, which wascalculated taking the unexpected reference measurement RM1 into account,is within the threshold amount and (ii) the reference measurement RM2 iscloser to the sensor measurement SM2 than the sensor measurement SM1,which was calculated without taking the unexpected reference measurementRM1 into account. However, this is not required, and, in somealternative embodiments, the transceiver 101 may determine that bothreference measurements RM1 and RM2 are acceptable in a different way.For example and without limitation, in one alternative embodiment, thetransceiver 101 may determine that the reference measurements RM1 andRM2 are acceptable if only one of conditions (i) and (ii) is met.

In some embodiments, in step 810, the transceiver 101 may be unable todetermine that at least one of reference measurements RM1 and RM2 isacceptable if the difference between the reference measurement RM2 andthe sensor measurement SM1 is outside the threshold amount and thedifference between the reference measurement RM2 and the sensormeasurement SM2 is outside the threshold amount.

In some embodiments, if the transceiver 101 determines in step 810 thatthe reference measurement RM2 is acceptable and that the referencemeasurement RM1 is not acceptable, the unexpected calibration process800 may proceed from step 810 to a step 812 in which the transceiver 101may accept only the reference measurement RM2 (and not the referencemeasurement RM1) as a calibration point. In some non-limitingembodiments, accepting the reference measurement RM2 as a calibrationpoint may include storing the reference measurement RM2 in a calibrationpoint memory (e.g., a circular buffer). In some embodiments, in step812, the transceiver 101 may calibrate the conversion function used tocalculate analyte measurements from sensor data. In some non-limitingembodiments, the transceiver 101 may calibrate the conversion functionusing one or more of the calibration points stored in the calibrationpoint memory. In some embodiments, the one or more calibration pointsused to calibrate the conversion function may include the referencemeasurement RM2. In some embodiments, the unexpected calibration process800 may proceed from step 812 to a step 830 in which the transceiver 101leaves the unexpected calibration phase and enters a normal calibrationphase (e.g., the normal calibration phase 606 of FIG. 6). In the normalcalibration phase, the transceiver 101 may use the updated conversionfunction to calculate sensor measurements from subsequent sensor data.

In some embodiments, if the transceiver 101 determines in step 810 thatboth reference measurements RM1 and RM2 are acceptable, the unexpectedcalibration process 800 may proceed from step 810 to a step 814 in whichthe transceiver 101 may accept the reference measurements RM1 and RM2 ascalibration points. In some non-limiting embodiments, accepting thereference measurements RM1 and RM2 as calibration points may includestoring the reference measurements RM1 and RM2 in the calibration pointmemory. In some embodiments, in step 814, the transceiver 101 maycalibrate the conversion function used to calculate analyte measurementsfrom sensor data. In some non-limiting embodiments, the transceiver 101may calibrate the conversion function using one or more of thecalibration points stored in the calibration point memory. In someembodiments, the one or more calibration points used to calibrate theconversion function may include the reference measurements RM1 and RM2.In some embodiments, the unexpected calibration process 800 may proceedfrom step 814 to a step 830 in which the transceiver 101 leaves theunexpected calibration phase and enters a normal calibration phase(e.g., the normal calibration phase 606 of FIG. 6). In the normalcalibration phase, the transceiver 101 may use the updated conversionfunction to calculate sensor measurements from subsequent sensor data.

In some embodiments, if the transceiver 101 is unable to determine instep 810 that at least one of the reference measurements RM1 and RM2 isacceptable, the transceiver 101 may reject the reference measurementRM1, treat the reference measurement RM2 as unexpected, and try againone or more times to find one or more acceptable reference measurementsusing one or more additionally received reference measurements. Forexample, in some non-limiting embodiments, if the transceiver 101 isunable to determines in step 810 that at least one of the referencemeasurements RM1 and RM2 is acceptable, the unexpected calibrationprocess 800 may proceed from step 810 to a step 816 in which thetransceiver 101 determines whether the transceiver 101 has receivedsensor data (e.g., light and/or temperature measurements) from thesensor 100. In some non-limiting embodiments, if the sensor has receivedsensor data, the unexpected calibration process 800 may proceed fromstep 816 to a measurement calculation step 818. In some non-limitingembodiments, if the transceiver 101 has not received sensor data, theunexpected calibration process 800 may proceed from step 816 to a step820.

In some non-limiting embodiments, the unexpected calibration process 800may include the measurement calculation step 818. In some embodiments,the step 818 may include calculating a sensor measurement SM1 using thecurrent calibration function, which takes neither the rejected referencemeasurement RM1 nor the unexpected reference measurement RM2 intoaccount, and the received sensor data. In some embodiments, in step 818,the transceiver 101 may display the calculated sensor measurement SM1.In some non-limiting embodiments, the transceiver 101 may display thesensor measurement SM1 by transmitting it to the display device 105 fordisplay.

In some embodiments, the unexpected calibration process 800 may includea step 820 in which the transceiver 101 determines whether thetransceiver 101 has received a reference measurement RM3. The referencemeasurement RM3 may be, for example and without limitation, an SMBGmeasurement obtained from, for example and without limitation, afinger-stick blood sample. In some non-limiting embodiments, thetransceiver 101 may receive the reference measurement RM3 at least aperiod of time (e.g., 1 minute, 5 minutes, 10 minutes, 15 minutes, 30minutes, 1 hour, etc.) after receiving the unexpected referencemeasurement RM2. In some embodiments, the transceiver 101 may receivethe reference measurement RM3 from the display device 105. In somenon-limiting embodiments, after the period of time has passed since theunexpected reference measurement RM2 was received, the transceiver 101may cause the display device 105 to prompt a user for the referencemeasurement RM3, and, in response, the user may enter the referencemeasurement RM3 into the display device 105. If the transceiver 101 hasnot received a reference measurement RM3, the unexpected calibrationprocess 800 may proceed back to step 816 and continue using the currentcalibration function, which does not take the reference measurements RM1and RM2 into account, to calculate sensor measurements from sensor datauntil a reference measurement RM3 is received. If the transceiver 101has received a reference measurement RM3, the unexpected calibrationprocess 800 may proceed from step 820 to a step 822.

In some embodiments, the unexpected calibration process 800 may includea step 822 in which the transceiver 101 calculates a sensor measurementSM2 using a conversion function that takes the unexpected referencemeasurement RM2 (but not the rejected reference measurement RM1) intoaccount as a calibration point. In some non-limiting embodiments, instep 822, the transceiver 101 may additionally calculate a sensormeasurement SM1 using a conversion function that takes into accountneither of the reference measurements RM1 and RM2 as calibration points.

In some embodiments, the unexpected calibration process 800 may includea step 824 in which the transceiver 101 determines whether one or moreof the reference measurements RM2 and RM3 are acceptable. In somenon-limiting embodiments, the step 824 may include comparing thereference measurement RM3 with the most-recent sensor measurement SM1,which was calculated by a conversion function that did not take theunexpected reference measurement RM2 into account, and with the sensormeasurement SM2, which was calculated by a conversion function that didtake the unexpected reference measurement RM2 into account.

In some non-limiting embodiments, the step 824 may include determiningwhether there is a large discrepancy between the reference measurementRM3 and one or more of the sensor measurements SM1 and SM2. Innon-limiting some embodiments, the transceiver 101 may determine whetherthe difference between the reference measurement RM3 and the sensormeasurement SM1 is within a threshold amount and whether the differencebetween the reference measurement RM3 and the sensor measurement SM2 iswithin the threshold amount. In some non-limiting embodiments, thethreshold amount may be a percentage of or deviation from sensormeasurement SM1. In some non-limiting embodiments, the threshold amountmay be a fixed, or the threshold amount may vary (e.g., based on thereference measurement RM3, sensor measurement SM1, or sensor measurementSM2). In some non-limiting embodiments, the step 824 may includedetermining whether the reference measurement RM3 is closer to thesensor measurement SM1 or to the sensor measurement SM2.

In some embodiments, in step 824, the transceiver 101 may determine thatreference measurement RM3 is acceptable if the transceiver 101determines both that (i) the difference between the referencemeasurement RM3 and the sensor measurement SM1, which was calculatedwithout taking the unexpected reference measurement RM2 into account, iswithin the threshold amount and (ii) the reference measurement RM3 iscloser to the sensor measurement SM1 than the sensor measurement SM2,which was calculated taking the unexpected reference measurement RM2into account. However, this is not required, and, in some alternativeembodiments, the transceiver 101 may determine that the referencemeasurement RM3 is acceptable in a different way. For example andwithout limitation, in one alternative embodiment, the transceiver 101may determine that the reference measurement RM3 is acceptable if onlyone of conditions (i) and (ii) is met.

In some embodiments, in step 824, the transceiver 101 may determine thatboth reference measurements RM2 and RM3 are acceptable if thetransceiver 101 determines both that (i) the difference between thereference measurement RM3 and the sensor measurement SM2, which wascalculated taking the unexpected reference measurement RM2 into account,is within the threshold amount and (ii) the reference measurement RM3 iscloser to the sensor measurement SM2 than the sensor measurement SM1,which was calculated without taking the unexpected reference measurementRM2 into account. However, this is not required, and, in somealternative embodiments, the transceiver 101 may determine that bothreference measurements RM2 and RM3 are acceptable in a different way.For example and without limitation, in one alternative embodiment, thetransceiver 101 may determine that the reference measurements RM2 andRM3 are acceptable if only one of conditions (i) and (ii) is met.

In some embodiments, in step 824, the transceiver 101 may be unable todetermine that at least one of reference measurements RM2 and RM3 isacceptable if the difference between the reference measurement RM3 andthe sensor measurement SM1 is outside the threshold amount and thedifference between the reference measurement RM3 and the sensormeasurement SM2 is outside the threshold amount.

In some embodiments, if the transceiver 101 determines in step 824 thatthe reference measurement RM3 is acceptable and that the unexpectedreference measurement RM2 is not acceptable, the unexpected calibrationprocess 800 may proceed from step 824 to a step 826 in which thetransceiver 101 may accept only the reference measurement RM3 (and notthe reference measurement RM2) as a calibration point. In somenon-limiting embodiments, accepting the reference measurement RM3 as acalibration point may include storing the reference measurement RM3 inthe calibration point memory. In some embodiments, in step 826, thetransceiver 101 may calibrate the conversion function used to calculateanalyte measurements from sensor data. In some non-limiting embodiments,the transceiver 101 may calibrate the conversion function using one ormore of the calibration points stored in the calibration point memory.In some embodiments, the one or more calibration points used tocalibrate the conversion function may include the reference measurementRM3. In some embodiments, the unexpected calibration process 800 mayproceed from step 826 to a step 830 in which the transceiver 101 leavesthe unexpected calibration phase and enters a normal calibration phase(e.g., the normal calibration phase 606 of FIG. 6). In the normalcalibration phase, the transceiver 101 may use the updated conversionfunction to calculate sensor measurements from subsequent sensor data.

In some embodiments, if the transceiver 101 determines in step 824 thatboth reference measurements RM2 and RM3 are acceptable, the unexpectedcalibration process 800 may proceed from step 824 to a step 828 in whichthe transceiver 101 may accept the reference measurements RM2 and RM3 ascalibration points. In some non-limiting embodiments, accepting thereference measurements RM2 and RM3 as calibration points may includestoring the reference measurements RM2 and RM3 in the calibration pointmemory. In some embodiments, in step 828, the transceiver 101 maycalibrate the conversion function used to calculate analyte measurementsfrom sensor data. In some non-limiting embodiments, the transceiver 101may calibrate the conversion function using one or more of thecalibration points stored in the calibration point memory. In someembodiments, the one or more calibration points used to calibrate theconversion function may include the reference measurements RM2 and RM3.In some embodiments, the unexpected calibration process 800 may proceedfrom step 828 to a step 830 in which the transceiver 101 leaves theunexpected calibration phase and enters a normal calibration phase(e.g., the normal calibration phase 606 of FIG. 6). In the normalcalibration phase, the transceiver 101 may use the updated conversionfunction to calculate sensor measurements from subsequent sensor data.

In some embodiments, if the transceiver 101 is unable to determine instep 824 that at least one of the reference measurements RM2 and RM3 isacceptable, the transceiver 101 may reject the reference measurementsRM2 and RM3, and the unexpected calibration process 800 may proceed fromstep 824 to a step 832 in which the transceiver 101 leaves theunexpected calibration phase and enters a drop out phase (e.g., the dropout phase 610 of FIG. 6). However, this is not required, and, in somealternative embodiments, in step 832, the transceiver 101 may enter aninitialization phase (e.g., the initialization phase 604 of FIG. 6)instead of entering the drop out phase. In some other alternativeembodiments, instead of rejecting both reference measurements RM2 andRM3 and entering a drop out or initialization phase, the transceiver 101may reject the reference measurement RM2, treat the referencemeasurement RM3 as unexpected, stay in the unexpected calibration phase,and try again one or more times to find one or more acceptable referencemeasurements using one or more additionally received referencemeasurements (e.g., a reference measurement RM4).

FIG. 9 is a flow chart illustrating an alternative unexpectedcalibration process 900, which may be performed during the unexpectedcalibration phase 608 of the control process 600 illustrated in FIG. 6.In some embodiments, the transceiver 101 may perform one or more stepsof the alternative unexpected calibration process 900. In somenon-limiting embodiments, the PIC microcontroller 920 of the transceiver101 may perform one or more steps of the alternative unexpectedcalibration process 900.

In some embodiments, the alternative unexpected calibration process 900may include a step 901 in which the transceiver 101 stores theunexpected reference measurement RM1 in a calibration point memory(e.g., a circular buffer). In some non-limiting embodiments, thealternative unexpected calibration process 900 may use the unexpectedreference measurement RM1 as a calibration point in the calculation anddisplay of subsequent sensor measurements (at least until a referencemeasurement RM2 is received). In some non-limiting embodiments, thealternative unexpected calibration process 900 may proceed from step 901to a step 902.

In some embodiments, the alternative unexpected calibration process 900may include a step 902 in which the transceiver 101 determines whetherthe transceiver 101 has received sensor data (e.g., light and/ortemperature measurements) from the sensor 100. In some non-limitingembodiments, if the sensor has received sensor data, the alternativeunexpected calibration process 900 may proceed from step 902 to ameasurement calculation step 904. In some non-limiting embodiments, ifthe transceiver 101 has not received sensor data, the alternativeunexpected calibration process 900 may proceed from step 902 to a step906.

In some non-limiting embodiments, the alternative unexpected calibrationprocess 900 may include the measurement calculation step 904. In someembodiments, the step 904 may include calculating a sensor measurementSM2 using the received sensor data and a conversion function that takesthe unexpected reference measurement RM1 into account as a calibrationpoint. In some embodiments, in step 904, the transceiver 101 may displaythe calculated sensor measurement SM2. In some non-limiting embodiments,the transceiver 101 may display the sensor measurement SM2 bytransmitting it to the display device 105 for display.

In some embodiments, the alternative unexpected calibration process 900may include a step 906 in which the transceiver 101 determines whetherthe transceiver 101 has received a reference measurement RM2. Thereference measurement RM2 may be, for example and without limitation, anSMBG measurement obtained from, for example and without limitation, afinger-stick blood sample. In some non-limiting embodiments, thetransceiver 101 may receive the reference measurement RM2 at least aperiod of time (e.g., 1 minute, 5 minutes, 10 minutes, 15 minutes, 30minutes, 1 hour, etc.) after receiving the unexpected referencemeasurement RM1. In some embodiments, the transceiver 101 may receivethe reference measurement RM2 from the display device 105. In somenon-limiting embodiments, after the period of time has passed since theunexpected reference measurement RM1 was received, the transceiver 101may cause the display device 105 to prompt a user for the referencemeasurement RM2, and, in response, the user may enter the referencemeasurement RM2 into the display device 105. If the transceiver 101 hasnot received a reference measurement RM2, the alternative unexpectedcalibration process 900 may proceed back to step 902 and continue usingthe calibration function that takes the reference measurement RM1 intoaccount to calculate sensor measurements from sensor data until areference measurement RM2 is received. If the transceiver 101 hasreceived a reference measurement RM2, the alternative unexpectedcalibration process 900 may proceed to a step 908.

In some embodiments, the alternative unexpected calibration process 900may include a step 908 in which the transceiver 101 calculates a sensormeasurement SM1 using a conversion function that does not take theunexpected reference measurement RM1 into account as a calibrationpoint. In some non-limiting embodiments, in step 908, the transceiver101 may additionally calculate a sensor measurement SM2 using theconversion function that takes the unexpected reference measurement RM1into account as a calibration point.

In some embodiments, the alternative unexpected calibration process 900may include a step 910 in which the transceiver 101 determines whetherone or more of the reference measurements RM1 and RM2 are acceptable. Insome non-limiting embodiments, the step 910 may include comparing thereference measurement RM2 with the most-recent sensor measurement SM2,which was calculated by a conversion function that did take theunexpected reference measurement RM1 into account, and with the sensormeasurement SM1, which was calculated by a conversion function that didnot take the unexpected reference measurement RM1 into account.

In some non-limiting embodiments, the step 910 may include determiningwhether there is a large discrepancy between the reference measurementRM2 and one or more of the sensor measurements SM1 and SM2. Innon-limiting some embodiments, the transceiver 101 may determine whetherthe difference between the reference measurement RM2 and the sensormeasurement SM1 is within a threshold amount and whether the differencebetween the reference measurement RM2 and the sensor measurement SM2 iswithin the threshold amount. In some non-limiting embodiments, thethreshold amount may be a percentage of or deviation from sensormeasurement SM1. In some non-limiting embodiments, the threshold amountmay be a fixed, or the threshold amount may vary (e.g., based on thereference measurement RM2, sensor measurement SM1, or sensor measurementSM2). In some non-limiting embodiments, the step 910 may includedetermining whether the reference measurement RM2 is closer to thesensor measurement SM1 or sensor measurement SM2.

In some embodiments, in step 910, the transceiver 101 may determine thatreference measurement RM2 is acceptable if the transceiver 101determines both that (i) the difference between the referencemeasurement RM2 and the sensor measurement SM1, which was calculatedwithout taking the unexpected reference measurement RM1 into account, iswithin the threshold amount and (ii) the reference measurement RM2 iscloser to the sensor measurement SM1 than the sensor measurement SM2,which was calculated taking the unexpected reference measurement RM1into account. However, this is not required, and, in some alternativeembodiments, the transceiver 101 may determine that the referencemeasurement RM2 is acceptable in a different way. For example andwithout limitation, in one alternative embodiment, the transceiver 101may determine that the reference measurement RM2 is acceptable if onlyone of conditions (i) and (ii) is met.

In some embodiments, in step 910, the transceiver 101 may determine thatboth reference measurements RM1 and RM2 are acceptable if thetransceiver 101 determines both that (i) the difference between thereference measurement RM2 and the sensor measurement SM2, which wascalculated taking the unexpected reference measurement RM1 into account,is within the threshold amount and (ii) the reference measurement RM2 iscloser to the sensor measurement SM2 than the sensor measurement SM1,which was calculated without taking the unexpected reference measurementRM1 into account. However, this is not required, and, in somealternative embodiments, the transceiver 101 may determine that bothreference measurements RM1 and RM2 are acceptable in a different way.For example and without limitation, in one alternative embodiment, thetransceiver 101 may determine that the reference measurements RM1 andRM2 are acceptable if only one of conditions (i) and (ii) is met.

In some embodiments, in step 910, the transceiver 101 may be unable todetermine that at least one of reference measurements RM1 and RM2 isacceptable if the difference between the reference measurement RM2 andthe sensor measurement SM1 is outside the threshold amount and thedifference between the reference measurement RM2 and the sensormeasurement SM2 is outside the threshold amount.

In some embodiments, if the transceiver 101 determines in step 910 thatthe reference measurement RM2 is acceptable and that the referencemeasurement RM1 is not acceptable, the alternative unexpectedcalibration process 900 may proceed from step 910 to a step 912 in whichthe transceiver 101 may accept only the reference measurement RM2 (andnot the reference measurement RM1) as a calibration point. In somenon-limiting embodiments, accepting only the reference measurement RM2as a calibration point may include storing the reference measurement RM2in the calibration point memory. In some non-limiting embodiments,accepting only the reference measurement RM2 as a calibration point mayinclude removing or deleting the reference measurement RM1 from thecalibration point memory.

In some embodiments, in step 912, the transceiver 101 may calibrate theconversion function used to calculate analyte measurements from sensordata. In some non-limiting embodiments, the transceiver 101 maycalibrate the conversion function using one or more of the calibrationpoints stored in the calibration point memory. In some embodiments, theone or more calibration points used to calibrate the conversion functionmay include the reference measurement RM2. In some embodiments, thealternative unexpected calibration process 900 may proceed from step 912to a step 930 in which the transceiver 101 leaves the unexpectedcalibration phase and enters a normal calibration phase (e.g., thenormal calibration phase 606 of FIG. 6). In the normal calibrationphase, the transceiver 101 may use the updated conversion function tocalculate sensor measurements from subsequent sensor data.

In some embodiments, if the transceiver 101 determines in step 910 thatboth reference measurements RM1 and RM2 are acceptable, the alternativeunexpected calibration process 900 may proceed from step 910 to a step914 in which the transceiver 101 may accept the reference measurementsRM1 and RM2 as calibration points. In some non-limiting embodiments,accepting the reference measurements RM1 and RM2 as calibration pointsmay include storing the reference measurement RM2 in the calibrationpoint memory along with the reference measurement RM1, which was storedin the calibration point memory in step 902. In some embodiments, instep 914, the transceiver 101 may calibrate the conversion function usedto calculate analyte measurements from sensor data. In some non-limitingembodiments, the transceiver 101 may calibrate the conversion functionusing one or more of the calibration points stored in the calibrationpoint memory. In some embodiments, the one or more calibration pointsused to calibrate the conversion function may include the referencemeasurements RM1 and RM2. In some embodiments, the alternativeunexpected calibration process 900 may proceed from step 914 to a step930 in which the transceiver 101 leaves the unexpected calibration phaseand enters a normal calibration phase (e.g., the normal calibrationphase 606 of FIG. 6). In the normal calibration phase, the transceiver101 may use the updated conversion function to calculate sensormeasurements from subsequent sensor data.

In some embodiments, if the transceiver 101 is unable to determine instep 910 that at least one of the reference measurements RM1 and RM2 isacceptable, the alternative unexpected calibration process 900 mayproceed to a step 915 in which the transceiver 101 may reject thereference measurement RM1, remove/delete the reference measurement RM1from the calibration point memory, store the reference measurement RM2in the calibration point memory, and treat the reference measurement RM2as unexpected. In some embodiments, the alternative unexpectedcalibration process 900 may try again one or more times to find one ormore acceptable reference measurements using one or more additionallyreceived reference measurements. For example, in some non-limitingembodiments, the alternative unexpected calibration process 900 mayproceed from step 915 to a step 916 in which the transceiver 101determines whether the transceiver 101 has received sensor data (e.g.,light and/or temperature measurements) from the sensor 100. In somenon-limiting embodiments, if the sensor has received sensor data, thealternative unexpected calibration process 900 may proceed from step 916to a measurement calculation step 918. In some non-limiting embodiments,if the transceiver 101 has not received sensor data, the alternativeunexpected calibration process 900 may proceed from step 916 to a step920.

In some non-limiting embodiments, the alternative unexpected calibrationprocess 900 may include the measurement calculation step 918. In someembodiments, the step 918 may include calculating a sensor measurementSM2 using the received data and a calibration function that takes theunexpected reference measurement RM2 into account (but does not take therejected reference measurement RM1 into account). In some embodiments,in step 918, the transceiver 101 may display the calculated sensormeasurement SM2. In some non-limiting embodiments, the transceiver 101may display the sensor measurement SM2 by transmitting it to the displaydevice 105 for display.

In some embodiments, the alternative unexpected calibration process 900may include a step 920 in which the transceiver 101 determines whetherthe transceiver 101 has received a reference measurement RM3. Thereference measurement RM3 may be, for example and without limitation, anSMBG measurement obtained from, for example and without limitation, afinger-stick blood sample. In some non-limiting embodiments, thetransceiver 101 may receive the reference measurement RM3 at least aperiod of time (e.g., 1 minute, 5 minutes, 10 minutes, 15 minutes, 30minutes, 1 hour, etc.) after receiving the unexpected referencemeasurement RM2. In some embodiments, the transceiver 101 may receivethe reference measurement RM3 from the display device 105. In somenon-limiting embodiments, after the period of time has passed since theunexpected reference measurement RM2 was received, the transceiver 101may cause the display device 105 to prompt a user for the referencemeasurement RM3, and, in response, the user may enter the referencemeasurement RM3 into the display device 105. If the transceiver 101 hasnot received a reference measurement RM3, the alternative unexpectedcalibration process 900 may proceed back to step 916 and continue usingthe calibration function that takes the reference measurement RM2 intoaccount to calculate sensor measurements from sensor data until areference measurement RM3 is received. If the transceiver 101 hasreceived a reference measurement RM3, the alternative unexpectedcalibration process 900 may proceed from step 920 to a step 922.

In some embodiments, the alternative unexpected calibration process 900may include a step 922 in which the transceiver 101 calculates a sensormeasurement SM1 using a conversion function that takes the neither theunexpected reference measurement RM2 nor the rejected referencemeasurement RM1 into account as a calibration point. In somenon-limiting embodiments, in step 922, the transceiver 101 mayadditionally calculate a sensor measurement SM2 using a conversionfunction that takes the unexpected reference measurement RM2 (but notthe rejected reference measurement RM1) into account.

In some embodiments, the alternative unexpected calibration process 900may include a step 924 in which the transceiver 101 determines whetherone or more of the reference measurements RM2 and RM3 are acceptable. Insome non-limiting embodiments, the step 924 may include comparing thereference measurement RM3 with the most-recent sensor measurement SM2,which was calculated by a conversion function that took the unexpectedreference measurement RM2 into account, and with the sensor measurementSM1, which was calculated by a conversion function that did not take theunexpected reference measurement RM2 into account.

In some non-limiting embodiments, the step 924 may include determiningwhether there is a large discrepancy between the reference measurementRM3 and one or more of the sensor measurements SM1 and SM2. Innon-limiting some embodiments, the transceiver 101 may determine whetherthe difference between the reference measurement RM3 and the sensormeasurement SM1 is within a threshold amount and whether the differencebetween the reference measurement RM3 and the sensor measurement SM2 iswithin the threshold amount. In some non-limiting embodiments, thethreshold amount may be a percentage of or deviation from sensormeasurement SM1. In some non-limiting embodiments, the threshold amountmay be a fixed, or the threshold amount may vary (e.g., based on thereference measurement RM3, sensor measurement SM1, or sensor measurementSM2). In some non-limiting embodiments, the step 924 may includedetermining whether the reference measurement RM3 is closer to thesensor measurement SM1 or to the sensor measurement SM2.

In some embodiments, in step 924, the transceiver 101 may determine thatreference measurement RM3 is acceptable if the transceiver 101determines both that (i) the difference between the referencemeasurement RM3 and the sensor measurement SM1, which was calculatedwithout taking the unexpected reference measurement RM2 into account, iswithin the threshold amount and (ii) the reference measurement RM3 iscloser to the sensor measurement SM1 than the sensor measurement SM2,which was calculated taking the unexpected reference measurement RM2into account. However, this is not required, and, in some alternativeembodiments, the transceiver 101 may determine that the referencemeasurement RM3 is acceptable in a different way. For example andwithout limitation, in one alternative embodiment, the transceiver 101may determine that the reference measurement RM3 is acceptable if onlyone of conditions (i) and (ii) is met.

In some embodiments, in step 924, the transceiver 101 may determine thatboth reference measurements RM2 and RM3 are acceptable if thetransceiver 101 determines both that (i) the difference between thereference measurement RM3 and the sensor measurement SM2, which wascalculated taking the unexpected reference measurement RM2 into account,is within the threshold amount and (ii) the reference measurement RM3 iscloser to the sensor measurement SM2 than the sensor measurement SM1,which was calculated without taking the unexpected reference measurementRM2 into account. However, this is not required, and, in somealternative embodiments, the transceiver 101 may determine that bothreference measurements RM2 and RM3 are acceptable in a different way.For example and without limitation, in one alternative embodiment, thetransceiver 101 may determine that the reference measurements RM2 andRM3 are acceptable if only one of conditions (i) and (ii) is met.

In some embodiments, in step 924, the transceiver 101 may be unable todetermine that at least one of reference measurements RM2 and RM3 isacceptable if the difference between the reference measurement RM3 andthe sensor measurement SM1 is outside the threshold amount and thedifference between the reference measurement RM3 and the sensormeasurement SM2 is outside the threshold amount.

In some embodiments, if the transceiver 101 determines in step 924 thatthe reference measurement RM3 is acceptable and that the unexpectedreference measurement RM2 is not acceptable, the alternative unexpectedcalibration process 900 may proceed from step 924 to a step 926 in whichthe transceiver 101 may accept only the reference measurement RM3 (andnot the reference measurement RM2) as a calibration point. In somenon-limiting embodiments, accepting only the reference measurement RM3as a calibration point may include storing the reference measurement RM3in the calibration point memory. In some non-limiting embodiments,accepting only the reference measurement RM3 as a calibration point mayinclude removing or deleting the reference measurement RM2 in thecalibration point memory. In some embodiments, in step 926, thetransceiver 101 may calibrate the conversion function used to calculateanalyte measurements from sensor data. In some non-limiting embodiments,the transceiver 101 may calibrate the conversion function using one ormore of the calibration points stored in the calibration point memory.In some embodiments, the one or more calibration points used tocalibrate the conversion function may include the reference measurementRM3. In some embodiments, the alternative unexpected calibration process900 may proceed from step 926 to a step 930 in which the transceiver 101leaves the unexpected calibration phase and enters a normal calibrationphase (e.g., the normal calibration phase 606 of FIG. 6). In the normalcalibration phase, the transceiver 101 may use the updated conversionfunction to calculate sensor measurements from subsequent sensor data.

In some embodiments, if the transceiver 101 determines in step 924 thatboth reference measurements RM2 and RM3 are acceptable, the alternativeunexpected calibration process 900 may proceed from step 924 to a step928 in which the transceiver 101 may accept the reference measurementsRM2 and RM3 as calibration points. In some non-limiting embodiments,accepting the reference measurements RM2 and RM3 as calibration pointsmay include storing the reference measurement RM3 in the calibrationpoint memory along with the reference measurement RM2, which was storedin the calibration point memory in step 915. In some embodiments, instep 928, the transceiver 101 may calibrate the conversion function usedto calculate analyte measurements from sensor data. In some non-limitingembodiments, the transceiver 101 may calibrate the conversion functionusing one or more of the calibration points stored in the calibrationpoint memory. In some embodiments, the one or more calibration pointsused to calibrate the conversion function may include the referencemeasurements RM2 and RM3. In some embodiments, the alternativeunexpected calibration process 900 may proceed from step 928 to a step930 in which the transceiver 101 leaves the unexpected calibration phaseand enters a normal calibration phase (e.g., the normal calibrationphase 606 of FIG. 6). In the normal calibration phase, the transceiver101 may use the updated conversion function to calculate sensormeasurements from subsequent sensor data.

In some embodiments, if the transceiver 101 is unable to determine instep 924 that at least one of the reference measurements RM2 and RM3 isacceptable, the transceiver 101 may reject the reference measurementsRM2 and RM3 and remove/delete the reference measurement RM2 from thecalibration point memory, and the alternative unexpected calibrationprocess 900 may proceed from step 924 to a step 932 in which thetransceiver 101 leaves the unexpected calibration phase and enters adrop out phase (e.g., the drop out phase 610 of FIG. 6). However, thisis not required, and, in some alternative embodiments, in step 932, thetransceiver 101 may enter an initialization phase (e.g., theinitialization phase 604 of FIG. 6) instead of entering the drop outphase. In some other alternative embodiments, instead of rejecting bothreference measurements RM2 and RM3 and entering a drop out orinitialization phase, the transceiver 101 may reject the referencemeasurement RM2, remove or delete the reference measurement RM2 from thecalibration point memory, store the reference measurement RM3 in thecalibration point memory, treat the reference measurement RM3 asunexpected, stay in the unexpected calibration phase, and try again oneor more times to find one or more acceptable reference measurementsusing one or more additionally received reference measurements (e.g., areference measurement RM4).

FIG. 10 is a flow chart illustrating another alternative unexpectedcalibration process 1000, which may be performed during the unexpectedcalibration phase 608 of the control process 600 illustrated in FIG. 6.In some embodiments, the transceiver 101 may perform one or more stepsof the other alternative unexpected calibration process 1000. In somenon-limiting embodiments, the PIC microcontroller 920 of the transceiver101 may perform one or more steps of the other alternative unexpectedcalibration process 1000.

In some embodiments, the other alternative unexpected calibrationprocess 1000 may include one or more steps that are the same as orsimilar to steps included in the unexpected calibration process 800. Forexample, as shown in FIG. 10, the other alternative unexpectedcalibration process 1000 may include one or more of steps 802, 804, 806,808, 812, 814, 816, 820, 826, 828, and 830, which are described abovewith reference to FIG. 8.

In some embodiments, the other alternative unexpected calibrationprocess 1000 may include a step 1010, which may be the same as step 810of the unexpected calibration process 800 except for one or more of thefollowing differences. In step 1010, if the transceiver 101 is unable todetermine that at least one of the reference measurements RM1 and RM2 isacceptable (e.g., because the transceiver 101 determines that (i) thedifference between the reference measurement RM2 and the sensormeasurement SM1 is outside the threshold amount and (ii) the differencebetween the reference measurement RM2 and the sensor measurement SM2 isoutside the threshold amount), the transceiver 101 may treat thereference measurement RM2 as unexpected and proceed to a step 1015 inwhich the reference measurement RM1 is accepted (instead of rejectingthe reference measurement as in step 808 of the unexpected calibrationprocess 800).

In some embodiments, in step 1015, the transceiver 101 may accept thereference measurement RM1 as a calibration point. In some non-limitingembodiments, accepting the reference measurement RM1 as a calibrationpoint may include storing the reference measurement RM1 in a calibrationpoint memory (e.g., a circular buffer). In some embodiments, in step1015, the transceiver 101 may calibrate the conversion function used tocalculate analyte measurements from sensor data. In some non-limitingembodiments, the transceiver 101 may calibrate the conversion functionusing one or more of the calibration points stored in the calibrationpoint memory. In some embodiments, the one or more calibration pointsused to calibrate the conversion function may include the referencemeasurement RM1. In some embodiments, the other alternative unexpectedcalibration process 1000 may proceed from step 1015 and try again one ormore times to find one or more acceptable reference measurements usingone or more additionally received reference measurements.

In some embodiments, the other alternative unexpected calibrationprocess 1000 may include a measurement calculation step 1018, which maybe performed if the transceiver 101 determines that it has receivedsensor data (e.g., light and/or temperature measurements) from thesensor 100 in step 816. In some embodiments, step 1018 may be the sameas step 818 of the unexpected calibration process 800 except for one ormore of the following differences. In some embodiments, the step 1018may include calculating a sensor measurement SM1 using the currentcalibration function, which takes the reference measurement RM1 intoaccount but does not take the unexpected reference measurement RM2 intoaccount, and the received sensor data. In some embodiments, in step1018, the transceiver 101 may display the calculated sensor measurementSM1. In some non-limiting embodiments, the transceiver 101 may displaythe sensor measurement SM1 by transmitting it to the display device 105for display.

In some embodiments, the other alternative unexpected calibrationprocess 1000 may include a measurement calculation step 1022, which maybe performed if the transceiver 101 determines that the transceiver 101has received a reference measurement RM3 in step 820. In someembodiments, step 1022 may be the same as step 822 of the unexpectedcalibration process 800 except for one or more of the followingdifferences. In some embodiments, in step 1022, the transceiver 101 maycalculate a sensor measurement SM2 using a conversion function thattakes the unexpected reference measurement RM2 (and the referencemeasurement RM1) into account as a calibration point. In somenon-limiting embodiments, in step 1022, the transceiver 101 mayadditionally calculate a sensor measurement SM1 using a conversionfunction that takes into account the reference measurement RM1 (but notthe reference measurement RM2) as a calibration point.

In some embodiments, the other alternative unexpected calibrationprocess 1000 may include a step 1024, which may be the same as step 824of the unexpected calibration process 800 except for one or more of thefollowing differences. In step 1024, if the transceiver 101 is unable todetermine that at least one of the reference measurements RM2 and RM3 isacceptable, the transceiver 101 may reject the reference measurementsRM2 and RM3, and the other alternative unexpected calibration process1000 may proceed from step 1024 to a step 1032 in which the transceiver101 leaves the unexpected calibration phase and enters a drop out phase(e.g., the drop out phase 610 of FIG. 6). However, this is not required,and, in some alternative embodiments, in step 1032, the transceiver 101may enter an initialization phase (e.g., the initialization phase 604 ofFIG. 6) instead of entering the drop out phase. In some otheralternative embodiments, instead of rejecting both referencemeasurements RM2 and RM3 and entering a drop out or initializationphase, the transceiver 101 may accept the reference measurement RM2,treat the reference measurement RM3 as unexpected, stay in theunexpected calibration phase, and try again one or more times to findone or more acceptable reference measurements using one or moreadditionally received reference measurements (e.g., a referencemeasurement RM4).

FIG. 11 is a flow chart illustrating an additional alternativeunexpected calibration process 1100, which may be performed during theunexpected calibration phase 608 of the control process 600 illustratedin FIG. 6. In some embodiments, the transceiver 101 may perform one ormore steps of the additional alternative unexpected calibration process1100. In some non-limiting embodiments, the PIC microcontroller 920 ofthe transceiver 101 may perform one or more steps of the additionalalternative unexpected calibration process 1100.

In some embodiments, the additional alternative unexpected calibrationprocess 1100 may include one or more steps that are the same as orsimilar to steps included in the alternative unexpected calibrationprocess 900. For example, as shown in FIG. 11, the additionalalternative unexpected calibration process 1100 may include one or moreof steps 901, 902, 904, 906, 908, 912, 914, 916, 920, 926, 928, and 930,which are described above with reference to FIG. 9.

In some embodiments, the additional alternative unexpected calibrationprocess 1100 may include a step 1110, which may be the same as step 910of the alternative unexpected calibration process 900 except for one ormore of the following differences. In step 1110, if the transceiver 101is unable to determine that at least one of the reference measurementsRM1 and RM2 is acceptable (e.g., because the transceiver 101 determinesthat (i) the difference between the reference measurement RM2 and thesensor measurement SM1 is outside the threshold amount and (ii) thedifference between the reference measurement RM2 and the sensormeasurement SM2 is outside the threshold amount), the transceiver 101may proceed to a step 1115 in which the reference measurement RM1 isaccepted (instead of being rejected and removed/deleted from thecalibration point memory as in step 915 of the alternative unexpectedcalibration process 900).

In some embodiments, in step 1115, the transceiver 101 may accept thereference measurement RM1, store the reference measurement RM2 in thecalibration point memory (e.g., a circular buffer), and treat thereference measurement RM2 as unexpected. In some embodiments, theadditional alternative unexpected calibration process 1100 may try againone or more times to find one or more acceptable reference measurementsusing one or more additionally received reference measurements.

In some non-limiting embodiments, the additional alternative unexpectedcalibration process 1100 may include the measurement calculation step1118. In some embodiments, the step 1118 may include calculating asensor measurement SM2 using the received data and a calibrationfunction that takes the unexpected reference measurement RM2 (and theaccepted reference measurement RM1) into account. In some embodiments,in step 1118, the transceiver 101 may display the calculated sensormeasurement SM2. In some non-limiting embodiments, the transceiver 101may display the sensor measurement SM2 by transmitting it to the displaydevice 105 for display.

In some embodiments, the additional alternative unexpected calibrationprocess 1100 may include a step 1122 in which the transceiver 101calculates a sensor measurement SM1 using a conversion function thatdoes not take the unexpected reference measurement RM2 into account (butdoes take the accepted reference measurement RM1 into account) as acalibration point. In some non-limiting embodiments, in step 1122, thetransceiver 101 may additionally calculate a sensor measurement SM2using a conversion function that takes the unexpected referencemeasurement RM2 (and the rejected reference measurement RM1) intoaccount.

In some embodiments, the additional alternative unexpected calibrationprocess 1100 may include a step 1124, which may be the same as step 924of the alternative unexpected calibration process 900 except for one ormore of the following differences. In step 1124, if the transceiver 101is unable to determine that at least one of the reference measurementsRM2 and RM3 is acceptable, the transceiver 101 may reject the referencemeasurements RM2 and RM3 and remove/delete the reference measurement RM2from the calibration point memory, and the additional alternativeunexpected calibration process 1100 may proceed from step 1124 to a step1132 in which the transceiver 101 leaves the unexpected calibrationphase and enters a drop out phase (e.g., the drop out phase 610 of FIG.6). However, this is not required, and, in some alternative embodiments,in step 1132, the transceiver 101 may enter an initialization phase(e.g., the initialization phase 604 of FIG. 6) instead of entering thedrop out phase. In some other alternative embodiments, instead ofrejecting both reference measurements RM2 and RM3 and entering a dropout or initialization phase, the transceiver 101 may accept thereference measurement RM2, store the reference measurement RM3 in thecalibration point memory, treat the reference measurement RM3 asunexpected, stay in the unexpected calibration phase, and try again oneor more times to find one or more acceptable reference measurementsusing one or more additionally received reference measurements (e.g., areference measurement RM4).

FIG. 12 is a flow chart illustrating an alternative process 1200 forcontrolling initialization and calibration of an analyte monitoringsystem 50. In some embodiments, the transceiver 101 may perform one ormore steps of the alternative control process 1200. In some non-limitingembodiments, the PIC microcontroller 920 of the transceiver 101 mayperform one or more steps of the alternative control process 1200. Insome embodiments, the alternative process 1200 may begin after insertionor implantation of the analyte sensor 100.

In some embodiments, the alternative control process 1200 may includeone or more phases that are the same as or similar to phases included inthe control process 600 described above with reference to FIG. 6. Forexample, as shown in FIG. 12, the alternative control process 1200 mayinclude one or more of phases 602, 604, 608, and 610, which aredescribed above with reference to FIG. 6.

In some embodiments, the alternative control process 1200 may includeone or more of a warm up phase 602, an initialization phase 604, anormal calibration phase 1206, an unexpected calibration phase 608, adrop out phase 610, and an expected calibration phase 1212. In somenon-limiting embodiments, after sensor insertion or implantation, thealternative control process 1200 may proceed from the warm up phase 602to the initialization phase 604 and then to the normal calibration phase1206. In some embodiments, the normal calibration phase 1206 of thealternative control process 1200 may be the same as the normalcalibration phase 606 of the control process 600 except that the normalcalibration phase 1206 may additionally determine whether an acceptedreference measurement is an expected reference measurement.

In some embodiments, in the normal calibration phase 1206, thetransceiver 101 may determine whether an accepted reference measurementis an expected reference measurement based on a comparison of theaccepted reference measurement to the most-recent sensor measurement(i.e., the most-recent analyte measurement calculated by the conversionfunction using received sensor data). In some embodiments, if there isno more than a small discrepancy between the accepted referencemeasurement and the most-recent sensor measurement, the transceiver 101may determine that the accepted reference measurement is an expectedreference measurement and proceed to an expected calibration phase 1212.

In some embodiments, during the expected calibration phase 1212, thetransceiver 101 may lower the frequency at which reference measurementsare received (relative to the frequency at which reference measurementsare received in the normal calibration phase 1206). For example, in somenon-limiting embodiments, in the expected calibration phase 1212, thetransceiver 101 may cause the display device 105 to prompt a user forreference measurements less frequently than a rate at which the displaydevice 105 prompts a user for reference measurements in the normalcalibration phase 1206. In some non-limiting embodiments, the user mayenter one or more reference measurements into the display device 105 inresponse to the prompts, and the display device 105 may convey the oneor more reference measurements to the transceiver 101.

In some embodiments, in the expected calibration phase 1212, thetransceiver 101 may determine whether to accept a received referencemeasurement or to treat the reference measurement as unexpected. In somenon-limiting embodiments, the transceiver 101 may determine whether toaccept a received reference measurement by comparing the referencemeasurement to the most-recent sensor measurement (i.e., the most-recentanalyte measurement calculated by the conversion function using receivedsensor data). In some embodiments, if the transceiver 101 determinesthat a reference measurement is unexpected, the alternative controlprocess 1200 may proceed from the expected calibration phase 1212 to anunexpected calibration phase 608. In some embodiments, if thetransceiver 101 determines that the reference measurement is acceptable,the transceiver 101 may calibrate (or re-calibrate or update) theconversion function using the reference point as a calibration point. Insome embodiments, the transceiver 101 may determine whether an acceptedreference measurement is an expected reference measurement. In someembodiments, if the transceiver 101 determines that the referencemeasurement is expected, the alternative control process 1200 may stayin the expected calibration phase 1212. In some embodiments, if thetransceiver 101 does not determine that the reference measurement isexpected, the alternative control process 1200 may proceed from theexpected calibration phase 1212 to a normal calibration phase 1206.

FIG. 13 is a flow chart illustrating an alternative normal calibrationprocess 1300, which may be performed during the normal calibration phase1206 of the alternative control process 1200 illustrated in FIG. 12. Insome embodiments, the transceiver 101 may perform one or more steps ofthe alternative normal calibration process 1300. In some non-limitingembodiments, the PIC microcontroller 920 of the transceiver 101 mayperform one or more steps of the alternative normal calibration process1300.

In some embodiments, the alternative normal calibration process 1300 mayinclude one or more steps that are the same as or similar to stepsincluded in the normal calibration process 700 described above withreference to FIG. 7. For example, as shown in FIG. 13, the alternativenormal calibration process 1300 may include one or more of steps 702,704, 706, 708, 710, and 712, which are described above with reference toFIG. 7. In some embodiments, the alternative normal calibration process1300 may additionally include steps 1314 and 1316.

In some non-limiting embodiments, in step 1314, the transceiver 101 maydetermine whether an accepted reference measurement RM1 is expected. Insome non-limiting embodiments, the step 1314 may reuse the results ofthe comparison of the reference measurement RM1 and the most-recentsensor measurement SM1 (i.e., the most-recent analyte measurementcalculated by the conversion function using received sensor data) thatwas performed in step 708. However, this is not required, and, in somealternative embodiments, step 1314 may include performing its owncomparison. In some non-limiting embodiments, the step 1314 may includedetermining whether there is no more than a small discrepancy betweenthe reference measurement RM1 and the most-recent sensor measurementSM1. In some non-limiting embodiments, the transceiver 101 may determinethat a reference measurement RM1 is expected if there is no more than asmall discrepancy between the reference measurement RM1 and themost-recent sensor measurement SM1. In non-limiting some embodiments,the transceiver 101 may determine that the reference measurement isexpected if the difference between the reference measurement RM1 and thesensor measurement SM1 is within a threshold amount. In somenon-limiting embodiments, the threshold amount may be a percentage ofthe sensor measurement SM1 (e.g., ±5% of SM1) or a deviation of thesensor measurement SM1 (e.g., ±3 mg/dL of SM1).

In some non-limiting embodiments, the threshold amount may be a fixedthreshold. However, this is not required, and, in some alternativeembodiments, the threshold amount may vary. In some non-limitingalternative embodiments, the threshold amount may vary based on one ormore of the sensor measurement SM1 and the reference measurement RM1. Insome non-limiting embodiments where the threshold amount varies based onreference amount RM1, the reference measurement range may be dividedinto two or more sub-ranges, and the transceiver 101 may use a differentthreshold for each of the sub-ranges. That is, in some non-limitingembodiments, if the reference measurement RM1 falls into a secondreference measurement sub-range, the transceiver 101 may use a secondthreshold when determining whether the reference measurement RM1 isacceptable. For example and without limitation, in one non-limitingalternative embodiment where the threshold amount varies based onreference measurement sub-ranges, the reference measurement range may bedivided into the following five sub-ranges: (i) less than 70 mg/dL, (ii)greater than or equal to 70 mg/dL and less than 140 mg/dL, (iii) greaterthan or equal to 140 mg/dL and less than 180 mg/dL, (iv) greater than orequal to 180 mg/dL and less than 240 mg/dL, and (v) greater than orequal to 240 mg/dL, and the transceiver 101 may use a differentthreshold amount for each of the five sub-ranges. However, this is notrequired, and some alternative embodiments may use different sub-rangesand/or a different number of sub-ranges. In some other alternativeembodiments having a varying threshold amount, the transceiver 101 mayuse a linear or non-linear formula to calculate the threshold amountthat should be used for a particular reference measurement RM1 or sensormeasurement SM1.

In some embodiments, if the transceiver 101 determines that thereference measurement RM1 is expected, the alternative normalcalibration process 1300 may proceed from step 1314 to step 1316 inwhich the transceiver 101 leaves the normal calibration phase and entersan expected calibration phase (e.g., the expected calibration phase 1212of FIG. 12). In some embodiments, if the transceiver 101 does notdetermine that the reference measurement RM1 is expected, thealternative normal calibration process 1300 may proceed from step 1314to step 702.

FIG. 14 is a flow chart illustrating an expected calibration process1400, which may be performed during the expected calibration phase 1212of the alternative control process 1200 illustrated in FIG. 12. In someembodiments, the transceiver 101 may perform one or more steps of theexpected calibration process 1400. In some non-limiting embodiments, thePIC microcontroller 920 of the transceiver 101 may perform one or moresteps of the expected calibration process 1400.

In some embodiments, the expected calibration process 1400 may includeone or more steps that are the same as or similar to steps included inthe normal calibration process 700 described above with reference toFIG. 7. For example, as shown in FIG. 14, the expected calibrationprocess 1400 may include one or more of steps 702, 704, 706, 708, 710,and 712, which are described above with reference to FIG. 7. In someembodiments, the expected calibration process 1400 may additionallyinclude steps 1401, 1414, 1416, and 1418.

In some non-limiting embodiments, in step 1401, the transceiver 101 maylower the frequency at which reference measurements are received(relative to the frequency at which reference measurements are receivedin the normal calibration phase 1206). For example, in some non-limitingembodiments, in the expected calibration phase 1212, the transceiver 101may cause the display device 105 to prompt a user for referencemeasurements less frequently than a rate at which the display device 105prompts a user for reference measurements in the normal calibrationphase 1206. For example and without limitation, in some non-limitingembodiments, the transceiver 101 may lower the frequency at whichreference measurements are received to approximately every 18 hours orapproximately every 24 hours (compared to, for example and withoutlimitation, approximately every 12 hours in the normal calibration phase1206). In some non-limiting embodiments, the user may enter one or morereference measurements into the display device 105 in response to theprompts, and the display device 105 may convey the one or more referencemeasurements to the transceiver 101.

In some non-limiting embodiments, in step 1414, the transceiver 101 maydetermine whether an accepted reference measurement RM1 is expected. Insome non-limiting embodiments, step 1414 of the expected calibrationprocess 1400 may be the same as step 1314 of the alternative normalcalibration process 1300 except for the following differences. First, ifthe transceiver 101 determines that the reference measurement RM1 isexpected in step 1414, the expected calibration process 1400 may proceedto step 702. Second, if the transceiver 101 does not determine that thereference measurement RM1 is expected in step 1414, the expectedcalibration process 1400 may proceed to a step 1416 in which thetransceiver 101 increases the frequency at which reference measurementsare received (e.g., by returning frequency to that used in the normalcalibration phase 1206) before returning to the normal calibration phase1206 in step 1418.

Embodiments of the present invention have been fully described abovewith reference to the drawing figures. Although the invention has beendescribed based upon these preferred embodiments, it would be apparentto those of skill in the art that certain modifications, variations, andalternative constructions could be made to the described embodimentswithin the spirit and scope of the invention.

What is claimed is:
 1. A method of calibrating an analyte sensor usingone or more reference measurements, the method comprising: receiving afirst reference analyte measurement (RM1); determining that the RM1 isunexpected; after determining that the RM1 is unexpected, receiving asecond reference analyte measurement (RM2); determining that one or moreof the RM1 and the RM2 are acceptable as calibration points; acceptingone or more of the RM1 and the RM2 as calibration points; andcalibrating the analyte sensor using at least one or more of the RM1 andthe RM2 as calibration points.
 2. The method of claim 1, wherein the RM1is a self-monitoring blood glucose (SMBG) measurement obtained from afinger-stick blood sample.
 3. The method of claim 1, wherein determiningthat the RM1 is unexpected comprises determining that the RM1 is notwithin a threshold amount of a sensor analyte measurement.
 4. The methodof claim 3, wherein the threshold amount varies based on one or more ofthe sensor analyte measurement and the RM1.
 5. The method of claim 1,further comprising: receiving sensor data from the analyte sensor; usingthe sensor data to calculate a first sensor analyte measurement (SM1)without RM1 as a calibration point; and using the sensor data tocalculate a second sensor analyte measurement (SM2) with the RM1 as acalibration point.
 6. The method of claim 5, wherein determining thatone or more of the RM1 and the RM2 are acceptable as calibration pointscomprises comparing the RM2 with one or more of the SM1 and the SM2. 7.The method of claim 6, wherein determining that one or more of the RM1and the RM2 are acceptable as calibration points further comprises:determining that the difference between the RM2 and the SM2 is within athreshold amount; and determining that the RM2 is closer to the SM2 thanto the SM1.
 8. The method of claim 7, wherein accepting one or more ofthe RM1 and the RM2 as calibration points comprises accepting both theRM1 and the RM2 as calibration points.
 9. The method of claim 8, whereincalibrating the analyte sensor uses at least the RM1 and the RM2 ascalibration points
 10. The method of claim 6, wherein determining thatone or more of the RM1 and the RM2 are acceptable as calibration pointscomprises: determining that the difference between the RM2 and the SM1is within the threshold amount; and determining that the RM2 is closerto the SM1 than to the SM2.
 11. The method of claim 10, whereinaccepting one or more of the RM1 and the RM2 as calibration pointscomprises accepting the RM2 as a calibration point and not accepting theRM1 as a calibration point.
 12. The method of claim 11, whereincalibrating the analyte sensor uses at least the RM2 as a calibrationpoint and does not use the RM1 as a calibration point.
 13. The method ofclaim 1, wherein accepting one or more of the RM1 and the RM2 ascalibration points comprises storing one or more of the RM1 and the RM2in a calibration point memory.
 14. The method of claim 1, whereincalibrating the analyte sensor comprises calibrating a conversionfunction used to convert sensor data received from the analyte sensorinto a sensor analyte measurement.
 15. The method of claim 1, furthercomprising storing the unexpected RM1 in a calibration point memory;wherein determining that one or more of the RM1 and the RM2 areacceptable as calibration points comprises determining that the RM2 isacceptable and that the RM1 is not acceptable; and wherein the methodfurther comprises, in response to determining that RM1 is notacceptable, deleting the RM1 from the calibration point memory.
 16. Amethod of calibrating an analyte sensor using one or more referencemeasurements, the method comprising: receiving a first reference analytemeasurement (RM1); determining that the RM1 is unexpected; afterdetermining that the RM1 is unexpected, receiving a second referenceanalyte measurement (RM2); determining that the RM2 is unexpected; afterdetermining that the RM2 is unexpected, receiving a third referenceanalyte measurement (RM3); accepting one or more of the RM2 and the RM3as calibration points; and calibrating the analyte sensor using at leastone or more of the RM2 and the RM3 as calibration points.
 17. The methodof claim 16, further comprising, after determining that the RM2 isunexpected, accepting the RM1.
 18. The method of claim 16, furthercomprising, after determining that the RM2 is unexpected, rejecting theRM1.
 19. A transceiver comprising: a sensor interface device configuredreceive sensor data conveyed by an analyte sensor; a display interfacedevice configured to convey information to a display device and toreceive information from the display device; and a processor configuredto: receive a first reference analyte measurement (RM1) from the displaydevice via the display interface device; determine that the RM1 isunexpected; after determining that the RM1 is unexpected, receive asecond reference analyte measurement (RM2) from the display device viathe display interface device; determine that one or more of the RM1 andthe RM2 are acceptable as calibration points; accept one or more of theRM1 and the RM2 as calibration points; and calibrate the analyte sensorusing at least one or more of the RM1 and the RM2 as calibration points.20. The transceiver of claim 19, wherein the sensor interface devicecomprises an antenna configured to receive wirelessly the sensor datafrom the analyte sensor.
 21. The transceiver of claim 19, wherein theprocessor is further configured to: use the sensor data to calculate afirst sensor analyte measurement (SM1) without RM1 as a calibrationpoint; and use the sensor data to calculate a second sensor analytemeasurement (SM2) with the RM1 as a calibration point.
 22. Thetransceiver of claim 21, wherein determining that one or more of the RM1and the RM2 are acceptable as calibration points comprises comparing theRM2 with one or more of the SM1 and the SM2.
 23. A transceivercomprising: a sensor interface device configured to to receive sensordata conveyed by an analyte sensor; a display interface deviceconfigured to convey information to a display device and to receiveinformation from the display device; and a processor configured to:receive a first reference analyte measurement (RM1) from the displaydevice via the display interface device; determine that the RM1 isunexpected; after determining that the RM1 is unexpected, receive asecond reference analyte measurement (RM2) from the display device viathe display interface device; determine that the RM2 is unexpected;after determining that the RM2 is unexpected, receive a third referenceanalyte measurement (RM3) from the display device via the displayinterface device; accept one or more of the RM2 and the RM3 ascalibration points; and calibrate the analyte sensor using at least oneor more of the RM2 and the RM3 as calibration points.
 24. Thetransceiver of claim 23, wherein the sensor interface device comprisesan antenna configured to receive wirelessly the sensor data from theanalyte sensor.
 25. The transceiver of claim 23, wherein the processoris further configured to: use the sensor data to calculate a firstsensor analyte measurement (SM1) without RM1 as a calibration point; anduse the sensor data to calculate a second sensor analyte measurement(SM2) with the RM1 as a calibration point.
 26. The transceiver of claim25, wherein determining that the RM2 is unexpected comprises comparingthe RM2 with one or more of the SM1 and the SM2.
 27. The transceiver ofclaim 23, wherein the processor is further configured to, afterdetermining that the RM2 is unexpected, accept the RM1.
 28. Thetransceiver of claim 23, wherein the processor is further configured to,after determining that the RM2 is unexpected, reject the RM1.
 29. Amethod comprising: receiving one or more reference analyte measurementsat a first rate; determining that a first reference analyte measurement(RM1) of the one or more reference analyte measurements received at thefirst rate is an expected reference analyte measurement; afterdetermining that the RM1 is an expected reference analyte measurement,receiving one or more reference analyte measurements at a second rate,wherein second rate is lower than the first rate.
 30. The method ofclaim 29, further comprising: determining that a second referenceanalyte measurement (RM2) of the one or more reference analytemeasurements received at the second rate is not an expected referenceanalyte measurement; after determining that the RM2 is not an expectedreference analyte measurement, receiving one or more reference analytemeasurements at the first rate.
 31. The method of claim 29, whereindetermining that the RM1 is an expected reference analyte measurementcomprises determining that the RM1 is within a threshold amount of asensor analyte measurement.
 32. The method of claim 29, furthercomprising, before determining that the RM1 is an expected referenceanalyte measurement, causing a display device to prompt a user forreference measurements at the first rate.
 33. The method of claim 29,further comprising, after determining that the RM1 is an expectedreference analyte measurement, causing a display device to prompt a userfor reference measurements at the second rate.
 34. The method of claim29, further comprising performing a calibration using the RM1 as acalibration point.
 35. A transceiver comprising: a display interfacedevice configured to convey information to a display device and toreceive information from the display device; and a processor configuredto: receive one or more reference analyte measurements from the displaydevice via the display interface device at a first rate; determinewhether a first reference analyte measurement (RM1) of the one or morereference analyte measurements received at the first rate is an expectedreference analyte measurement; after determining that the RM1 is anexpected reference analyte measurement, receive one or more referenceanalyte measurements from the display device via the display interfacedevice at a second rate, wherein second rate is lower than the firstrate.
 36. The transceiver of claim 35, wherein the processor is furtherconfigured to: determine that a second reference analyte measurement(RM2) of the one or more reference analyte measurements received at thesecond rate is not an expected reference analyte measurement; and afterdetermining that the RM2 is not an expected reference analytemeasurement, receive one or more reference analyte measurements from thedisplay device via the display interface device at the first rate. 37.The transceiver of claim 35, further comprising a sensor interfacedevice configured to receive sensor data conveyed by an analyte sensor;wherein determining that the RM1 is an expected reference analytemeasurement comprises determining that the RM1 is within a thresholdamount of a sensor analyte measurement calculated using the sensor datareceived from the analyte sensor via the sensor interface device. 38.The transceiver of claim 35, wherein the processor is further configuredto, before determining that the RM1 is an expected reference analytemeasurement, cause a display device to prompt a user for referencemeasurements at the first rate.
 39. The transceiver of claim 35, whereinthe processor is further configured to, after determining that the RM1is an expected reference analyte measurement, cause a display device toprompt a user for reference measurements at the second rate.
 40. Thetransceiver of claim 35, wherein the processor is further configured toperform a calibration using the RM1 as a calibration point.